package overlay

import (
	"bytes"
	"errors"
	"fmt"
	"io/fs"
	"os"
	"path"
	"path/filepath"
	"reflect"
	"regexp"
	"strings"
	"sync"
	"text/template"
	"text/template/parse"

	"github.com/Masterminds/sprig/v3"
	"github.com/coreos/go-systemd/v22/unit"

	"github.com/warewulf/warewulf/internal/pkg/config"
	"github.com/warewulf/warewulf/internal/pkg/node"
	"github.com/warewulf/warewulf/internal/pkg/util"
	"github.com/warewulf/warewulf/internal/pkg/wwlog"
)

var ErrDoesNotExist = fmt.Errorf("overlay does not exist")

// Overlay represents an overlay directory path.
type Overlay string

// Name returns the base name of the overlay directory.
//
// This is derived from the full path of the overlay.
func (overlay Overlay) Name() string {
	return path.Base(overlay.Path())
}

// Path returns the string representation of the overlay path.
//
// This method allows the Overlay type to be easily converted back to its
// underlying string representation.
func (overlay Overlay) Path() string {
	return string(overlay)
}

// Rootfs returns the path to the root filesystem (rootfs) within the overlay.
//
// If the "rootfs" directory exists inside the overlay path, it returns the
// path to the "rootfs" directory. Otherwise, it checks if the overlay path
// itself is a directory and returns that. If neither exists, it defaults to
// returning the "rootfs" path.
func (overlay Overlay) Rootfs() string {
	rootfs := path.Join(overlay.Path(), "rootfs")
	if util.IsDir(rootfs) {
		return rootfs
	} else if util.IsDir(overlay.Path()) {
		return overlay.Path()
	} else {
		return rootfs
	}
}

// File constructs a full path to a file within the overlay's root filesystem.
//
// Parameters:
//   - filePath: The relative path of the file within the overlay.
//
// Returns:
//   - The full path to the specified file in the overlay's rootfs.
//     If the specified path is not contained within the overlay, the empty string is returned.
func (overlay Overlay) File(filePath string) string {
	rootfs := overlay.Rootfs()
	fullPath := path.Join(rootfs, filePath)
	cleanPath := filepath.Clean(fullPath)
	cleanRootfs := filepath.Clean(rootfs)
	rel, err := filepath.Rel(cleanRootfs, cleanPath)
	if err != nil {
		return ""
	}

	if strings.HasPrefix(rel, "..") {
		return ""
	}

	return cleanPath
}

// Exists checks whether the overlay path exists and is a directory.
//
// Returns:
//   - true if the overlay path exists and is a directory; false otherwise.
func (overlay Overlay) Exists() bool {
	return util.IsDir(overlay.Path())
}

// IsSiteOverlay determines whether the overlay is a site overlay.
//
// A site overlay is identified by its parent directory matching the configured
// site overlay directory path.
//
// Returns:
//   - true if the overlay is a site overlay; false otherwise.
func (overlay Overlay) IsSiteOverlay() bool {
	siteDir := filepath.Clean(config.Get().Paths.SiteOverlaydir())
	overlayPath := filepath.Clean(overlay.Path())
	if rel, err := filepath.Rel(siteDir, overlayPath); err != nil {
		return false
	} else {
		return !strings.HasPrefix(rel, "..")
	}
}

// IsDistributionOverlay determines whether the overlay is a distribution overlay.
//
// A distribution overlay is identified by its parent directory matching the configured
// distribution overlay directory path.
//
// Returns:
//   - true if the overlay is a distribution overlay; false otherwise.
func (overlay Overlay) IsDistributionOverlay() bool {
	siteDir := filepath.Clean(config.Get().Paths.DistributionOverlaydir())
	overlayPath := filepath.Clean(overlay.Path())
	if rel, err := filepath.Rel(siteDir, overlayPath); err != nil {
		return false
	} else {
		return !strings.HasPrefix(rel, "..")
	}
}

func (overlay Overlay) AddFile(filePath string, content []byte, parents bool, force bool) error {
	wwlog.Info("Creating file %s in overlay %s, force: %v", filePath, overlay.Name(), force)

	if !overlay.IsSiteOverlay() {
		siteOverlay, err := overlay.CloneToSite()
		if err != nil {
			return fmt.Errorf("failed to clone distribution overlay '%s' to site overlay: %w", overlay.Name(), err)
		}
		// replace the overlay with newly created siteOverlay
		overlay = siteOverlay
	}
	fullPath := overlay.File(filePath)
	// create necessary parent directories
	if parents {
		if err := os.MkdirAll(path.Dir(fullPath), 0o755); err != nil {
			return fmt.Errorf("failed to create parent directories for %s: %w", fullPath, err)
		}
	}

	// if the file already exists and force is false, return an error
	if util.IsFile(fullPath) {
		if force {
			return os.WriteFile(fullPath, content, 0o644)
		}
		return fmt.Errorf("file %s already exists in overlay %s", filePath, overlay.Name())
	}

	return os.WriteFile(fullPath, content, 0o644)
}

func (overlay Overlay) Delete(force bool) (err error) {
	wwlog.Info("Deleting overlay %s, force: %v", overlay.Name(), force)
	if overlay.IsDistributionOverlay() {
		return fmt.Errorf("cannot delete a distribution overlay: %s", overlay.Name())
	}
	if force {
		err := os.RemoveAll(overlay.Path())
		if err != nil {
			return fmt.Errorf("failed to delete overlay forcely: %w", err)
		}
	} else {
		// remove rootfs at first
		if err = os.Remove(overlay.Rootfs()); err != nil {
			return fmt.Errorf("failed to delete overlay: %w", err)
		}
		if overlay.Exists() {
			if err = os.Remove(overlay.Path()); err != nil {
				return fmt.Errorf("failed to delete overlay: %w", err)
			}
		}
	}
	return nil
}

// DeleteFile deletes a file or the entire overlay directory.
// before deletion.
func (overlay Overlay) DeleteFile(filePath string, force, cleanup bool) (err error) {
	wwlog.Info("Deleting file %s from overlay %s, force: %v, cleanup: %v", filePath, overlay.Name(), force, cleanup)
	// first check if file exists
	if !util.IsFile(overlay.File(filePath)) {
		return fmt.Errorf("file %s does not exist in overlay %s", filePath, overlay.Name())
	}
	if overlay.IsDistributionOverlay() {
		siteOverlay, err := overlay.CloneToSite()
		if err != nil {
			return fmt.Errorf("failed to clone distribution overlay '%s' to site overlay: %w", overlay.Name(), err)
		}
		// replace the overlay with newly created siteOverlay
		overlay = siteOverlay
	}
	fullPath := overlay.File(filePath)
	if force {
		if err := os.RemoveAll(fullPath); err != nil {
			return fmt.Errorf("failed to delete file %s from overlay %s: %w", filePath, overlay.Name(), err)
		}
	} else {
		if err := os.Remove(fullPath); err != nil {
			return fmt.Errorf("failed to delete file %s from overlay %s: %w", filePath, overlay.Name(), err)
		}
	}

	if cleanup {
		// cleanup the empty parents
		i := path.Dir(fullPath)
		for i != overlay.Rootfs() {
			wwlog.Debug("Evaluating directory to remove: %s", i)
			err := os.Remove(i)
			if err != nil {
				// if the directory is not empty, we stop here
				if !os.IsNotExist(err) {
					wwlog.Debug("Could not remove directory %s: %v", i, err)
				}
				break
			}
			wwlog.Debug("Removed empty directory: %s", i)
			i = path.Dir(i)
		}
	}
	return nil
}

// chmod for the given path in the overlay
func (overlay Overlay) Chmod(path string, mode uint64) (err error) {
	if !overlay.IsSiteOverlay() {
		overlay, err = overlay.CloneToSite()
		if err != nil {
			return err
		}
	}
	fullPath := overlay.File(path)
	if !util.IsFile(fullPath) && !util.IsDir(fullPath) {
		return fmt.Errorf("file does not exist within overlay: %s:%s", overlay.Name(), fullPath)
	}

	return os.Chmod(fullPath, os.FileMode(mode))
}

// chown file or dir in overlay
func (overlay Overlay) Chown(path string, uid, gid int) (err error) {
	if !overlay.IsSiteOverlay() {
		overlay, err = overlay.CloneToSite()
		if err != nil {
			return err
		}
	}
	fullPath := overlay.File(path)
	if !util.IsFile(fullPath) && !util.IsDir(fullPath) {
		return fmt.Errorf("file does not exist within overlay: %s:%s", overlay.Name(), fullPath)
	}
	return os.Chown(fullPath, uid, gid)
}

func (overlay Overlay) Mkdir(path string, mode int32) (err error) {
	if !overlay.IsSiteOverlay() {
		overlay, err = overlay.CloneToSite()
		if err != nil {
			return err
		}
	}
	fullPath := overlay.File(path)
	if util.IsFile(fullPath) || util.IsDir(fullPath) {
		wwlog.Warn("path already exists, overwriting permissions: %s:%s", overlay.Name(), fullPath)
	}
	return os.MkdirAll(fullPath, os.FileMode(mode))
}

// FieldInfo contains detailed type information about a template variable
type FieldInfo struct {
	Field      reflect.StructField // Complete field metadata including tags
	ParentType reflect.Type        // The containing struct type
	FullPath   string              // Full path like ".NetDevs.Ipaddr6"
	VarName    string              // Original variable name from template
}

// ParseVarFields returns detailed type information for each variable in the template
// by using reflection to resolve the actual struct fields being referenced.
func (overlay Overlay) ParseVarFields(file string) map[string]FieldInfo {
	if !strings.HasSuffix(file, ".ww") {
		return nil
	}
	fullPath := overlay.File(file)
	if !util.IsFile(fullPath) {
		wwlog.Error("Template file does not exist in overlay %s: %s", overlay.Name(), file)
		return nil
	}

	renderState := &RenderedTemplate{
		Files: []*RenderedFile{
			{Name: ""},
		},
	}
	renderWriter := &multiFileWriter{current: &renderState.Files[0].Buffer}
	funcMap := buildTemplateFuncMap(fullPath, TemplateStruct{}, renderState, renderWriter)
	tmpl, err := template.New(path.Base(fullPath)).Option("missingkey=default").Funcs(funcMap).ParseFiles(fullPath)
	if err != nil {
		wwlog.Error("Could not parse template file %s: %s", fullPath, err)
		return nil
	}

	result := make(map[string]FieldInfo)
	rootType := reflect.TypeOf(TemplateStruct{})

	// Track range variables and their types
	rangeVars := make(map[string]reflect.Type)
	// Initialize $ to refer to the root template context
	rangeVars["$"] = rootType

	if tmpl.Tree != nil && tmpl.Root != nil {
		walkParseTree(tmpl.Root, rootType, "", rangeVars, result)
	}

	return result
}

// ParseCommentVars parses a template file for comments that contain variable documentations.
// The comments must be in the format `{{/* key: value */}}`. The content is parsed as YAML.
func (overlay Overlay) ParseCommentVars(file string) (retMap map[string]string) {
	retMap = make(map[string]string)
	if !strings.HasSuffix(file, ".ww") {
		return nil
	}
	fullPath := overlay.File(file)
	if !util.IsFile(fullPath) {
		wwlog.Error("Template file does not exist in overlay %s: %s", overlay.Name(), file)
		return nil
	}

	content, err := os.ReadFile(fullPath)
	if err != nil {
		wwlog.Error("Could not read template file %s: %s", fullPath, err)
		return nil
	}

	re := regexp.MustCompile(`{{-?\s*/\*\s*(.*?):\s*(.*?)\s*\*/\s*-?}}`)
	matches := re.FindAllStringSubmatch(string(content), -1)
	if len(matches) > 0 {
		wwlog.Debug("matches: %v len(%d:%d)", matches, len(matches), len(matches[0]))
	} else {
		wwlog.Debug("matches: [] len(0)")
	}
	for i := range matches {
		if len(matches[i]) > 2 {
			retMap[matches[i][1]] = matches[i][2]
		}
	}
	return
}

// walkParseTree recursively traverses the template's parse tree and resolves
// variable references to actual struct fields using reflection.
func walkParseTree(node parse.Node, currentType reflect.Type, currentPath string, rangeVars map[string]reflect.Type, result map[string]FieldInfo) {
	if node == nil {
		return
	}

	switch n := node.(type) {
	case *parse.ActionNode:
		// Handle variable assignments like $var := expr
		if n.Pipe != nil && len(n.Pipe.Decl) > 0 && len(n.Pipe.Cmds) > 0 {
			// Try to resolve the type of the expression being assigned
			cmd := n.Pipe.Cmds[0]
			if len(cmd.Args) > 0 {
				// Check for field access (e.g., $NetDevs := .NetDevs)
				if field, ok := cmd.Args[0].(*parse.FieldNode); ok {
					fieldInfo := resolveFieldChain(currentType, field.Ident, currentPath)
					if fieldInfo != nil {
						// Record all declared variables with this type
						for _, decl := range n.Pipe.Decl {
							rangeVars[decl.Ident[0]] = fieldInfo.Field.Type
						}
					}
				} else if varNode, ok := cmd.Args[0].(*parse.VariableNode); ok {
					// Check for variable-to-variable assignment (e.g., $b := $a)
					if len(varNode.Ident) == 1 {
						// Simple variable reference
						varBaseName := varNode.Ident[0]
						if varType, exists := rangeVars[varBaseName]; exists {
							for _, decl := range n.Pipe.Decl {
								rangeVars[decl.Ident[0]] = varType
							}
						}
					}
				}
			}
		}
		walkParseTree(n.Pipe, currentType, currentPath, rangeVars, result)

	case *parse.IfNode:
		walkParseTree(n.Pipe, currentType, currentPath, rangeVars, result)
		walkParseTree(n.List, currentType, currentPath, rangeVars, result)
		walkParseTree(n.ElseList, currentType, currentPath, rangeVars, result)

	case *parse.ListNode:
		if n != nil {
			for _, child := range n.Nodes {
				walkParseTree(child, currentType, currentPath, rangeVars, result)
			}
		}

	case *parse.RangeNode:
		// Handle range statements like {{range $key, $val := .NetDevs}}
		// First, walk the pipe to record the variable being ranged over
		walkParseTree(n.Pipe, currentType, currentPath, rangeVars, result)

		if n.Pipe != nil && len(n.Pipe.Cmds) > 0 {
			// Get what's being ranged over to determine element type
			var fieldInfo *FieldInfo

			// Check for both FieldNode (e.g., .NetDevs) and VariableNode (e.g., $disk.PartitionList)
			rangeField := extractFieldFromPipe(n.Pipe)
			if rangeField != nil {
				// Resolve the type of the field being ranged over
				fieldInfo = resolveFieldChain(currentType, rangeField.Ident, currentPath)
			} else {
				// Check if it's a variable access
				for _, cmd := range n.Pipe.Cmds {
					for _, arg := range cmd.Args {
						if varNode, ok := arg.(*parse.VariableNode); ok {
							varBaseName := varNode.Ident[0]
							if varType, exists := rangeVars[varBaseName]; exists {
								if len(varNode.Ident) > 1 {
									// Multi-part variable like $disk.PartitionList
									fieldIdents := varNode.Ident[1:] // Skip the variable name
									fieldInfo = resolveFieldChain(varType, fieldIdents, currentPath)
								} else {
									// Simple variable like $NetDevs
									fieldInfo = &FieldInfo{
										Field: reflect.StructField{
											Name: varBaseName,
											Type: varType,
										},
										ParentType: currentType,
										FullPath:   currentPath,
									}
								}
								break
							}
						}
					}
					if fieldInfo != nil {
						break
					}
				}
			}

			if fieldInfo != nil {
				rangeType := fieldInfo.Field.Type

				// For slices and arrays, get the element type
				if rangeType.Kind() == reflect.Slice || rangeType.Kind() == reflect.Array {
					rangeType = rangeType.Elem()
				}

				// For maps, get the value type
				if rangeType.Kind() == reflect.Map {
					rangeType = rangeType.Elem()
				}

				// Dereference pointers
				if rangeType.Kind() == reflect.Ptr {
					rangeType = rangeType.Elem()
				}

				// Track the range variable assignments
				if len(n.Pipe.Decl) > 0 {
					if len(n.Pipe.Decl) == 2 {
						// Two-variable range: $key, $val := .Map or $index, $val := .Slice
						keyType := reflect.TypeOf(0) // Default to int for slice indices
						if fieldInfo.Field.Type.Kind() == reflect.Map {
							keyType = fieldInfo.Field.Type.Key()
						}
						rangeVars[n.Pipe.Decl[0].Ident[0]] = keyType   // First variable is key/index
						rangeVars[n.Pipe.Decl[1].Ident[0]] = rangeType // Second variable is value
					} else {
						// Single-variable range: $val := .Slice
						rangeVars[n.Pipe.Decl[0].Ident[0]] = rangeType
					}
				}

				// Walk the range body with the element type
				walkParseTree(n.List, rangeType, fieldInfo.FullPath, rangeVars, result)
			}
		}
		walkParseTree(n.ElseList, currentType, currentPath, rangeVars, result)

	case *parse.WithNode:
		walkParseTree(n.Pipe, currentType, currentPath, rangeVars, result)
		walkParseTree(n.List, currentType, currentPath, rangeVars, result)
		walkParseTree(n.ElseList, currentType, currentPath, rangeVars, result)

	case *parse.TemplateNode:
		walkParseTree(n.Pipe, currentType, currentPath, rangeVars, result)

	case *parse.PipeNode:
		if n != nil {
			for _, cmd := range n.Cmds {
				for _, arg := range cmd.Args {
					walkParseTree(arg, currentType, currentPath, rangeVars, result)
				}
			}
		}

	case *parse.FieldNode:
		// Field access like .Ipmi.Ipaddr or $netdev.Ipaddr
		varName := n.String()

		// Determine the base type for field resolution
		baseType := currentType
		basePath := currentPath

		// Check if this is a variable access (starts with $)
		if strings.HasPrefix(varName, "$") {
			// Extract variable name (e.g., "$netdev.Device" -> "netdev")
			parts := strings.SplitN(varName[1:], ".", 2)
			if len(parts) > 0 {
				varBaseName := parts[0]
				if varType, exists := rangeVars[varBaseName]; exists {
					baseType = varType
					basePath = currentPath
				}
			}
		}

		fieldInfo := resolveFieldChain(baseType, n.Ident, basePath)

		// If resolution failed, try adding "P" suffix to last identifier
		// This handles methods like Primary() backed by PrimaryP field
		if fieldInfo == nil && len(n.Ident) >= 1 {
			identWithP := make([]string, len(n.Ident))
			copy(identWithP, n.Ident)
			identWithP[len(identWithP)-1] += "P"
			fieldInfo = resolveFieldChain(baseType, identWithP, basePath)
			// Use the original variable name (without P)
			if fieldInfo != nil {
				fieldInfo.VarName = varName
			}
		}

		if fieldInfo != nil {
			if fieldInfo.VarName == "" {
				fieldInfo.VarName = varName
			}
			result[varName] = *fieldInfo
		}

	case *parse.VariableNode:
		// Variable reference like $netdev or possibly $netdev.Field
		varName := n.String()

		// Check if this is a simple variable or a field access on a variable
		if len(n.Ident) > 1 {
			// This is $var.Field or $var.Field.Method - handle like a FieldNode
			varBaseName := n.Ident[0]
			if varType, exists := rangeVars[varBaseName]; exists {
				// Resolve the field chain starting from the variable's type
				fieldIdents := n.Ident[1:] // Skip the variable name, keep the fields
				fieldInfo := resolveFieldChain(varType, fieldIdents, currentPath)

				// If resolution failed and we have multiple parts, the last part might be a method
				// Try resolving without the last identifier (e.g., OnBoot.BoolDefaultTrue -> OnBoot)
				if fieldInfo == nil && len(fieldIdents) > 1 {
					fieldIdents = fieldIdents[:len(fieldIdents)-1]
					fieldInfo = resolveFieldChain(varType, fieldIdents, currentPath)
					// Use a simplified variable name without the method
					if fieldInfo != nil {
						// Build simplified name: $varBaseName.field1.field2 (without method)
						simplifiedName := varBaseName
						for _, ident := range fieldIdents {
							simplifiedName += "." + ident
						}
						fieldInfo.VarName = simplifiedName
					}
				}

				// If resolution still failed, try adding "P" suffix to last identifier
				// This handles methods like Primary() backed by PrimaryP field
				if fieldInfo == nil && len(fieldIdents) >= 1 {
					// Try with "P" suffix on the last identifier
					fieldIdentsWithP := make([]string, len(fieldIdents))
					copy(fieldIdentsWithP, fieldIdents)
					fieldIdentsWithP[len(fieldIdentsWithP)-1] += "P"
					fieldInfo = resolveFieldChain(varType, fieldIdentsWithP, currentPath)
					// Use the original variable name (without P)
					if fieldInfo != nil {
						fieldInfo.VarName = varName
					}
				}

				if fieldInfo != nil {
					if fieldInfo.VarName == "" {
						fieldInfo.VarName = varName
					}
					result[fieldInfo.VarName] = *fieldInfo
				}
			}
		} else if len(n.Ident) == 1 {
			// Simple variable reference
			varBaseName := n.Ident[0]
			if varType, exists := rangeVars[varBaseName]; exists {
				result[varName] = FieldInfo{
					VarName:    varName,
					ParentType: varType,
					FullPath:   currentPath,
				}
			}
		}
	}
}

// extractFieldFromPipe extracts the FieldNode from a pipe (used in range statements)
func extractFieldFromPipe(pipe *parse.PipeNode) *parse.FieldNode {
	if pipe == nil || len(pipe.Cmds) == 0 {
		return nil
	}
	for _, cmd := range pipe.Cmds {
		for _, arg := range cmd.Args {
			if field, ok := arg.(*parse.FieldNode); ok {
				return field
			}
		}
	}
	return nil
}

// resolveFieldChain walks a chain of field identifiers (like ["Ipmi", "Ipaddr"])
// and returns the final field's information using reflection.
// Methods are resolved and reported. If a method has a backing field with "P" suffix,
// the backing field's metadata is used; otherwise, the method's return type is used.
func resolveFieldChain(rootType reflect.Type, idents []string, basePath string) *FieldInfo {
	if rootType.Kind() == reflect.Ptr {
		rootType = rootType.Elem()
	}

	if len(idents) == 0 {
		return nil
	}

	currentType := rootType
	fullPath := basePath
	var finalField reflect.StructField
	var parentType reflect.Type

	for i, fieldName := range idents {
		if currentType.Kind() != reflect.Struct {
			return nil
		}

		field, found := currentType.FieldByName(fieldName)
		if !found {
			// Field not found - try to find a method with this name
			// This handles methods like DiskList(), PartitionList(), Id(), ShouldExist()
			ptrType := reflect.PointerTo(currentType)
			method, methodFound := ptrType.MethodByName(fieldName)
			if !methodFound {
				return nil
			}

			// Get the method's return type (first return value)
			methodType := method.Type
			if methodType.NumOut() == 0 {
				return nil
			}
			returnType := methodType.Out(0)

			// Check if there's a backing field with "P" suffix
			// Only methods with backing fields should be reported as user-facing variables
			backingFieldName := fieldName + "P"
			backingField, backingFound := currentType.FieldByName(backingFieldName)

			// For the last identifier in the chain
			if i == len(idents)-1 {
				if backingFound {
					// Use the backing field's metadata (tags) but the method's return type
					// This gives us the documentation from ShouldExistP but the type from ShouldExist()
					finalField = reflect.StructField{
						Name: fieldName,
						Type: returnType, // Use method's return type, not backing field's type
						Tag:  backingField.Tag,
					}
					parentType = currentType
					fullPath += "." + fieldName // Use method name in path, not field name
					currentType = returnType
				} else {
					// No backing field - create a field with the method's return type
					// This allows documenting methods via comments
					finalField = reflect.StructField{
						Name: fieldName,
						Type: returnType,
					}
					parentType = currentType
					fullPath += "." + fieldName
					currentType = returnType
				}
			} else {
				// Not the last identifier - we're in the middle of a chain (e.g., DiskList in node.DiskList.PartitionList)
				// Continue walking with the method's return type for type resolution
				parentType = currentType
				fullPath += "." + fieldName
				currentType = returnType

				// We don't have a real field yet, just continue to next identifier
				// Don't set finalField here as we need to keep walking
				continue
			}
		} else {
			// Field found
			finalField = field
			parentType = currentType
			fullPath += "." + fieldName
			currentType = field.Type
		}

		// Dereference pointer types for next iteration
		if currentType.Kind() == reflect.Ptr {
			currentType = currentType.Elem()
		}

		// For map types, remaining identifiers are map keys, not fields
		if currentType.Kind() == reflect.Map && i < len(idents)-1 {
			// Append remaining path as map keys
			mapKeyPath := ""
			for j := i + 1; j < len(idents); j++ {
				mapKeyPath += "." + idents[j]
			}
			fullPath += mapKeyPath

			// Create a synthetic field with the map's value type
			// For Tags (map[string]string), accessing Tags.key should return string, not map[string]string
			valueType := currentType.Elem()
			return &FieldInfo{
				Field: reflect.StructField{
					Name: idents[len(idents)-1], // Use the last key as the field name
					Type: valueType,             // Use the map's value type
				},
				ParentType: parentType,
				FullPath:   fullPath,
			}
		}
	}

	return &FieldInfo{
		Field:      finalField,
		ParentType: parentType,
		FullPath:   fullPath,
	}
}

func BuildAllOverlays(nodes []node.Node, allNodes []node.Node, workerCount int) error {
	nodeChan := make(chan node.Node, len(nodes))
	errChan := make(chan error, len(nodes)*2)

	var wg sync.WaitGroup
	worker := func() {
		for n := range nodeChan {
			wwlog.Info("Building system overlay image for %s", n.Id())
			wwlog.Debug("System overlays for %s: [%s]", n.Id(), strings.Join(n.SystemOverlay, ", "))
			if len(n.SystemOverlay) < 1 {
				wwlog.Warn("No system overlays defined for %s", n.Id())
			}
			if err := BuildOverlay(n, allNodes, "system", n.SystemOverlay); err != nil {
				errChan <- fmt.Errorf("could not build system overlays %v for node %s: %w", n.SystemOverlay, n.Id(), err)
			}

			wwlog.Info("Building runtime overlay image for %s", n.Id())
			wwlog.Debug("Runtime overlays for %s: [%s]", n.Id(), strings.Join(n.RuntimeOverlay, ", "))
			if len(n.RuntimeOverlay) < 1 {
				wwlog.Warn("No runtime overlays defined for %s", n.Id())
			}
			if err := BuildOverlay(n, allNodes, "runtime", n.RuntimeOverlay); err != nil {
				errChan <- fmt.Errorf("could not build runtime overlays %v for node %s: %w", n.RuntimeOverlay, n.Id(), err)
			}
		}
		wg.Done()
	}

	for i := 0; i < workerCount; i++ {
		wg.Add(1)
		go worker()
	}
	for _, n := range nodes {
		nodeChan <- n
	}
	close(nodeChan)

	wg.Wait()
	close(errChan)

	for err := range errChan {
		return err
	}
	return nil
}

func BuildSpecificOverlays(nodes []node.Node, allNodes []node.Node, overlayNames []string, workerCount int) error {
	nodeChan := make(chan node.Node, len(nodes))
	errChan := make(chan error, len(nodes))

	var wg sync.WaitGroup
	worker := func() {
		for n := range nodeChan {
			wwlog.Info("Building overlay for %s: %v", n.Id(), overlayNames)
			for _, overlayName := range overlayNames {
				err := BuildOverlay(n, allNodes, "", []string{overlayName})
				if err != nil {
					errChan <- fmt.Errorf("could not build overlay %s for node %s: %w", overlayName, n.Id(), err)
				}
			}
		}
		wg.Done()
	}

	for i := 0; i < workerCount; i++ {
		wg.Add(1)
		go worker()
	}
	for _, n := range nodes {
		nodeChan <- n
	}
	close(nodeChan)

	wg.Wait()
	close(errChan)

	for err := range errChan {
		return err
	}
	return nil
}

/*
Build overlay for the host, so no argument needs to be given
*/
func BuildHostOverlay() error {
	hostname, _ := os.Hostname()
	hostData := node.NewNode(hostname)
	wwlog.Info("Building overlay for %s: host", hostname)
	hostdir, err := Get("host")
	if err != nil {
		return err
	}
	stats, err := os.Stat(hostdir.Rootfs())
	if err != nil {
		return fmt.Errorf("could not build host overlay: %w ", err)
	}
	if stats.Mode() != os.FileMode(0o750|os.ModeDir) && stats.Mode() != os.FileMode(0o700|os.ModeDir) {
		wwlog.SecWarn("Permissions of host overlay dir %s are %s (750 is considered as secure)", hostdir.Rootfs(), stats.Mode())
	}
	registry, err := node.New()
	if err != nil {
		return err
	}
	var allNodes []node.Node
	allNodes, err = registry.FindAllNodes()
	if err != nil {
		return err
	}
	return BuildOverlayIndir(hostData, allNodes, []string{"host"}, "/")
}

/*
Get all overlays present in warewulf
*/
func FindOverlays() (overlayList []string) {
	dotfilecheck, _ := regexp.Compile(`^\..*`)
	controller := config.Get()
	var files []fs.DirEntry
	if distfiles, err := os.ReadDir(controller.Paths.DistributionOverlaydir()); err != nil {
		wwlog.Warn("error reading overlays from %s: %s", controller.Paths.DistributionOverlaydir(), err)
	} else {
		files = append(files, distfiles...)
	}
	if sitefiles, err := os.ReadDir(controller.Paths.SiteOverlaydir()); err != nil {
		wwlog.Warn("error reading overlays from %s: %s", controller.Paths.SiteOverlaydir(), err)
	} else {
		files = append(files, sitefiles...)
	}
	for _, file := range files {
		wwlog.Debug("Evaluating overlay source: %s", file.Name())
		isdotfile := dotfilecheck.MatchString(file.Name())

		if file.IsDir() && !isdotfile && !util.InSlice(overlayList, file.Name()) {
			overlayList = append(overlayList, file.Name())
		}
	}
	return overlayList
}

/*
Build the given overlays for a node and create an image for them
*/
func BuildOverlay(nodeConf node.Node, allNodes []node.Node, context string, overlayNames []string) error {
	if len(overlayNames) == 0 && context == "" {
		return nil
	}

	// create the dir where the overlay images will reside
	var name string
	if context != "" {
		name = fmt.Sprintf("%s %s overlay", nodeConf.Id(), context)
	} else {
		name = fmt.Sprintf("%s overlay/%v", nodeConf.Id(), overlayNames)
	}
	overlayImage := Image(nodeConf.Id(), context, overlayNames)
	overlayImageDir := path.Dir(overlayImage)

	err := os.MkdirAll(overlayImageDir, 0o750)
	if err != nil {
		return fmt.Errorf("failed to create directory for %s: %s: %w", name, overlayImageDir, err)
	}

	wwlog.Debug("Created directory for %s: %s", name, overlayImageDir)

	buildDir, err := os.MkdirTemp(os.TempDir(), ".wwctl-overlay-")
	if err != nil {
		return fmt.Errorf("failed to create temporary directory for %s: %w", name, err)
	}
	defer func() {
		if err := os.RemoveAll(buildDir); err != nil {
			wwlog.Warn("failed to remove temporary build directory %s: %s", buildDir, err)
		}
	}()

	wwlog.Debug("Created temporary directory for %s: %s", name, buildDir)

	err = BuildOverlayIndir(nodeConf, allNodes, overlayNames, buildDir)
	if err != nil {
		return fmt.Errorf("failed to generate files for %s: %w", name, err)
	}

	wwlog.Debug("Generated files for %s", name)

	err = util.BuildFsImage(
		name,
		buildDir,
		overlayImage,
		[]string{"*"},
		[]string{},
		// ignore cross-device files
		true,
		"newc")

	return err
}

// Build the given overlays for a node in the given directory.
func BuildOverlayIndir(nodeData node.Node, allNodes []node.Node, overlayNames []string, outputDir string) error {
	if len(overlayNames) == 0 {
		return nil
	}
	if !util.IsDir(outputDir) {
		return fmt.Errorf("output must a be a directory: %s", outputDir)
	}

	if !util.ValidString("^[a-zA-Z0-9-._:]+$", strings.Join(overlayNames, "")) {
		return fmt.Errorf("overlay names contains illegal characters: %v", overlayNames)
	}

	wwlog.Verbose("Processing node/overlays: %s/%s", nodeData.Id(), strings.Join(overlayNames, ","))
	for _, overlayName := range overlayNames {
		wwlog.Verbose("Building overlay %s for node %s in %s", overlayName, nodeData.Id(), outputDir)
		overlayRootfs, err := Get(overlayName)
		if err != nil {
			return err
		}

		wwlog.Debug("Walking the overlay structure: %s", overlayRootfs.Rootfs())
		err = filepath.Walk(overlayRootfs.Rootfs(), func(walkPath string, info os.FileInfo, err error) error {
			if err != nil {
				return fmt.Errorf("error for %s: %w", walkPath, err)
			}
			wwlog.Debug("Found overlay file: %s", walkPath)

			relPath, relErr := filepath.Rel(overlayRootfs.Rootfs(), walkPath)
			if relErr != nil {
				wwlog.Warn("Error computing relative path for %s: %v", walkPath, relErr)
				return relErr
			}
			outputPath := path.Join(outputDir, relPath)

			if info.IsDir() {
				wwlog.Debug("Found directory: %s", walkPath)

				if err = os.MkdirAll(outputPath, info.Mode()); err != nil {
					return fmt.Errorf("could not create directory within overlay: %w", err)
				}
				if err = util.CopyUIDGID(walkPath, outputPath); err != nil {
					return fmt.Errorf("failed setting permissions on overlay directory: %w", err)
				}

				wwlog.Debug("Created directory in overlay: %s", outputPath)

			} else if filepath.Ext(walkPath) == ".ww" {
				originalOutputPath := outputPath
				defaultOutputPath := strings.TrimSuffix(outputPath, ".ww")
				tstruct, err := InitStruct(overlayName, nodeData, allNodes)
				if err != nil {
					return fmt.Errorf("failed to initial data for %s: %w", nodeData.Id(), err)
				}
				tstruct.BuildSource = walkPath
				wwlog.Verbose("Evaluating overlay template file: %s", walkPath)

				rendered, err := RenderTemplate(walkPath, tstruct)
				if err != nil {
					return fmt.Errorf("failed to render template %s: %w", walkPath, err)
				}
				if !rendered.WriteFile {
					return nil
				}

				// Write each output file. The default slot (Name == "") is written to
				// defaultOutputPath when it is the only file. When named files are also
				// present, the default slot is skipped unless it is a symlink: content
				// before the first file() call often includes template setup (variable
				// assignments, range headers) that produces incidental whitespace, and
				// writing it as a separate file would be unexpected. A softlink() call
				// before any file() call is always intentional and must be honored.
				// Named files are always written.
				for _, f := range rendered.Files {
					var filePath string
					if f.Name == "" {
						if len(rendered.Files) > 1 && !f.IsSymlink {
							continue
						}
						filePath = defaultOutputPath
					} else if path.IsAbs(f.Name) {
						// Anchor absolute paths under outputDir so they resolve within
						// the image. For the host overlay (outputDir == "/") this is a
						// no-op and the path writes to the real host location as intended.
						filePath = filepath.Join(outputDir, f.Name)
					} else {
						filePath = path.Join(path.Dir(originalOutputPath), f.Name)
					}

					// Guard against path traversal: verify the resolved path stays
					// within outputDir before writing or creating a symlink.
					if rel, relErr := filepath.Rel(filepath.Clean(outputDir), filepath.Clean(filePath)); relErr != nil || strings.HasPrefix(rel, "..") {
						return fmt.Errorf("file() path %q escapes output directory", f.Name)
					}

					// For absolute file() paths, ensure parent directories exist.
					// This applies to both regular files and symlinks: os.Symlink
					// fails with ENOENT if the parent directory does not exist.
					if path.IsAbs(f.Name) {
						parentDir := filepath.Dir(filePath)
						sourceDirInfo, err := os.Stat(path.Dir(walkPath))
						if err != nil {
							return fmt.Errorf("could not stat source directory: %w", err)
						}
						if err := os.MkdirAll(parentDir, sourceDirInfo.Mode()); err != nil {
							return fmt.Errorf("could not create parent directory for absolute path: %w", err)
						}
					}

					if f.IsSymlink {
						wwlog.Debug("Creating soft link %s -> %s", filePath, f.Target)
						if err = os.Symlink(f.Target, filePath); err != nil {
							return fmt.Errorf("could not create symlink from template: %w", err)
						}
					} else {
						wwlog.Debug("Writing file %s", f.Name)
						err = CarefulWriteBuffer(filePath, f.Buffer, rendered.BackupFile, info.Mode())
						if err != nil {
							return fmt.Errorf("could not write file from template: %w", err)
						}
						err = util.CopyUIDGID(walkPath, filePath)
						if err != nil {
							return fmt.Errorf("failed setting permissions on template output file: %w", err)
						}
					}
				}
			} else if info.Mode()&os.ModeSymlink == os.ModeSymlink {
				wwlog.Debug("Found symlink %s", walkPath)
				target, err := os.Readlink(walkPath)
				if err != nil {
					return fmt.Errorf("failed reading symlink: %w", err)
				}
				if util.IsFile(outputPath) {
					backupPath := outputPath + ".wwbackup"
					if !util.IsFile(backupPath) {
						wwlog.Debug("Output file already exists: moving to backup file")
						if err = os.Rename(outputPath, backupPath); err != nil {
							return fmt.Errorf("failed renaming to backup file: %w", err)
						}
					} else {
						wwlog.Debug("%s exists, keeping the backup file", backupPath)
						if err = os.Remove(outputPath); err != nil {
							return fmt.Errorf("failed removing existing file: %w", err)
						}
					}
				}
				if err = os.Symlink(target, outputPath); err != nil {
					return fmt.Errorf("failed creating symlink: %w", err)
				}
				wwlog.Debug("Created symlink file: %s", outputPath)
			} else {
				if err := util.CopyFile(walkPath, outputPath); err != nil {
					return fmt.Errorf("could not copy file into overlay: %w", err)
				}
				wwlog.Debug("Copied overlay file: %s", outputPath)
			}

			return nil
		})
		if err != nil {
			return fmt.Errorf("failed to build overlay image directory: %w", err)
		}
	}

	return nil
}

/*
Writes buffer to the destination file. If wwbackup is set a wwbackup will be created.
*/
func CarefulWriteBuffer(destFile string, buffer bytes.Buffer, backupFile bool, perm fs.FileMode) (err error) {
	wwlog.Debug("Trying to careful write file (%d bytes): %s", buffer.Len(), destFile)
	if backupFile {
		if !util.IsFile(destFile+".wwbackup") && util.IsFile(destFile) {
			err := util.CopyFile(destFile, destFile+".wwbackup")
			if err != nil {
				return fmt.Errorf("failed to create backup: %s -> %s.wwbackup %w", destFile, destFile, err)
			}
		}
	}
	w, err := os.OpenFile(destFile, os.O_WRONLY|os.O_CREATE|os.O_TRUNC, perm)
	if err != nil {
		return fmt.Errorf("could not open new file for template %w", err)
	}
	defer func() {
		if cerr := w.Close(); cerr != nil && err == nil {
			err = fmt.Errorf("failed to close file %s: %w", destFile, cerr)
		}
	}()
	_, err = buffer.WriteTo(w)
	return err
}

// errAbort is returned by the abort() template function to halt template execution
// at the exact point of the call. RenderTemplate catches this sentinel and sets
// result.WriteFile = false rather than propagating it as a real error.
var errAbort = errors.New("abort")

// RenderedFile represents one output file or symlink produced by a .ww template.
// Template rendering uses a state-based multi-file writer instead of post-processing
// sentinel strings. When a .ww template calls file("name"), the fileFn closure appends
// a RenderedFile to the result and redirects the multiFileWriter to that file's buffer.
// All subsequent template output flows into that buffer until the next file() call.
// This approach is whitespace-trim safe: the old sentinel approach broke when {{- -}}
// caused adjacent file() calls to collapse onto a single line, causing the greedy regex
// to match only the last sentinel.
//
// A RenderedFile with an empty Name is the default slot. It holds all template
// output when no file() calls are made, or the content written before the first
// file() call when file() calls are present. The default slot is always present
// in Files[0]; callers are responsible for deciding how to handle it.
type RenderedFile struct {
	Name      string
	IsSymlink bool
	Target    string
	Buffer    bytes.Buffer
}

// RenderedTemplate is the complete output of rendering a .ww template file.
// Files is always initialized with a default entry (Name == "") before rendering.
// When no file() calls are present, all content goes to that entry and it is the
// only element. When file() calls are present, named entries follow the default.
// The default entry is always present in Files[0] regardless of whether its
// buffer is empty; callers decide whether to act on it (see BuildOverlayIndir).
type RenderedTemplate struct {
	WriteFile  bool
	BackupFile bool
	Files      []*RenderedFile
}

type multiFileWriter struct {
	current *bytes.Buffer // redirected by file() and softlink() closures
}

func (w *multiFileWriter) Write(p []byte) (n int, err error) {
	return w.current.Write(p)
}

// buildTemplateFuncMap constructs the template FuncMap for a .ww template.
// result and writer are the shared mutable state closed over by the stateful
// template functions (file, softlink, ImportLink, abort, nobackup). They must
// be allocated by the caller so RenderTemplate and ParseVarFields can each
// supply their own isolated state.
func buildTemplateFuncMap(fileName string, data TemplateStruct, result *RenderedTemplate, writer *multiFileWriter) template.FuncMap {
	softlinkFn := func(target string) string {
		if len(result.Files) > 0 {
			last := result.Files[len(result.Files)-1]
			last.IsSymlink = true
			last.Target = target
		}
		return ""
	}

	importlinkFn := func(lnk string) (string, error) {
		resolvedTarget, err := filepath.EvalSymlinks(lnk)
		if err != nil {
			return "", fmt.Errorf("ImportLink: failed to resolve symlink %q: %w", lnk, err)
		}
		wwlog.Debug("importing softlink pointing to: %s", resolvedTarget)
		return softlinkFn(resolvedTarget), nil
	}

	// fileFn switches the active write target; returns "" so no output is emitted.
	fileFn := func(name string) string {
		f := &RenderedFile{Name: name}
		result.Files = append(result.Files, f)
		writer.current = &f.Buffer
		return ""
	}

	incFn := func(i int) int { return i + 1 }
	decFn := func(i int) int { return i - 1 }

	ignitionFn := func() string {
		return createIgnitionJson(data.ThisNode)
	}

	abortFn := func() (string, error) {
		wwlog.Debug("abort file called in %s", fileName)
		return "", errAbort
	}

	nobackupFn := func() string {
		wwlog.Debug("not backup for %s", fileName)
		result.BackupFile = false
		return ""
	}

	funcMap := template.FuncMap{
		"Include":           templateFileInclude,
		"IncludeFrom":       templateImageFileInclude,
		"IncludeBlock":      templateFileBlock,
		"ImportLink":        importlinkFn,
		"basename":          path.Base,
		"inc":               incFn,
		"dec":               decFn,
		"file":              fileFn,
		"softlink":          softlinkFn,
		"readlink":          filepath.EvalSymlinks,
		"IgnitionJson":      ignitionFn,
		"abort":             abortFn,
		"nobackup":          nobackupFn,
		"UniqueField":       UniqueField,
		"SystemdEscape":     unit.UnitNameEscape,
		"SystemdEscapePath": unit.UnitNamePathEscape,
	}

	for key, value := range sprig.TxtFuncMap() {
		funcMap[key] = value
	}
	return funcMap
}

// RenderTemplate renders the .ww template at fileName with the provided data,
// returning a RenderedTemplate that describes all output files. The file() and
// softlink() template functions update state directly rather than emitting
// sentinel strings, so they work correctly regardless of whitespace trimming.
func RenderTemplate(fileName string, data TemplateStruct) (*RenderedTemplate, error) {
	result := &RenderedTemplate{
		WriteFile:  true,
		BackupFile: true,
		Files:      []*RenderedFile{{Name: ""}},
	}
	writer := &multiFileWriter{current: &result.Files[0].Buffer}
	funcMap := buildTemplateFuncMap(fileName, data, result, writer)

	tmpl, err := template.New(path.Base(fileName)).Option("missingkey=default").Funcs(funcMap).ParseGlob(fileName)
	if err != nil {
		return nil, fmt.Errorf("could not parse template %s: %w", fileName, err)
	}

	if err = tmpl.Execute(writer, data); err != nil {
		if errors.Is(err, errAbort) {
			// abort() halts execution at the call site; content up to that point
			// is preserved in result.Files[0].Buffer for debugging via overlay show / API.
			result.WriteFile = false
		} else {
			return nil, fmt.Errorf("could not execute template: %w", err)
		}
	}

	return result, nil
}

// RenderTemplateFile is a wrapper around RenderTemplate for callers that only
// need a single rendered buffer. It returns the default slot (Files[0].Buffer):
// all content when the template makes no file() calls, or the content written
// before the first file() call when file() calls are present. Callers that need
// named output files or symlink information should use RenderTemplate directly.
func RenderTemplateFile(fileName string, data TemplateStruct) (
	buffer bytes.Buffer, backupFile, writeFile *bool,
	err error,
) {
	rendered, renderErr := RenderTemplate(fileName, data)
	if renderErr != nil {
		err = renderErr
		return
	}
	backupFile = &rendered.BackupFile
	writeFile = &rendered.WriteFile
	buffer = rendered.Files[0].Buffer
	return
}

// Get all the files as a string slice for a given overlay
func (overlay Overlay) GetFiles() (files []string, err error) {
	err = filepath.Walk(overlay.Rootfs(), func(path string, info fs.FileInfo, err error) error {
		if util.IsFile(path) {
			files = append(files, strings.TrimPrefix(path, overlay.Rootfs()))
		}
		return nil
	})
	return
}