package main

import (
	"encoding/json"
	"fmt"
	"image"
	"image/png"
	"log"
	"os"
	"path/filepath"
	"sort"
	"strings"
	"time"
)

func formerBaseDir() string {
	home, _ := os.UserHomeDir()
	return filepath.Join(home, "former")
}

func formerTempDir() string {
	return filepath.Join(formerBaseDir(), "temp")
}

func formerSessionsDir() string {
	return filepath.Join(formerBaseDir(), "sessions")
}

func formerProfilesDir() string {
	return filepath.Join(formerBaseDir(), "profiles")
}

func formerProjectsDir() string {
	return filepath.Join(formerBaseDir(), "projects")
}

func formerRecentPath() string {
	return filepath.Join(formerBaseDir(), "recent.json")
}

func ensureFormerDirs() {
	for _, d := range []string{formerTempDir(), formerProjectsDir()} {
		os.MkdirAll(d, 0755)
	}
}

// ======== .former Project Persistence ========

// CreateProject creates a new .former directory at the given path with an empty project.json.
func CreateProject(path string) (*ProjectData, error) {
	if !strings.HasSuffix(path, ".former") {
		path += ".former"
	}
	if err := os.MkdirAll(path, 0755); err != nil {
		return nil, fmt.Errorf("create project dir: %v", err)
	}
	for _, sub := range []string{"stencil", "enclosure", "vectorwrap", "structural", "scanhelper"} {
		os.MkdirAll(filepath.Join(path, sub), 0755)
	}

	proj := &ProjectData{
		ID:        randomID(),
		Name:      strings.TrimSuffix(filepath.Base(path), ".former"),
		CreatedAt: time.Now(),
		Version:   1,
		Settings:  ProjectSettings{ShowGrid: true},
	}
	if err := SaveProject(path, proj); err != nil {
		return nil, err
	}
	AddRecentProject(path, proj.Name)
	return proj, nil
}

// SaveProject atomically writes project.json inside a .former directory.
func SaveProject(path string, data *ProjectData) error {
	raw, err := json.MarshalIndent(data, "", "  ")
	if err != nil {
		return err
	}
	tmpPath := filepath.Join(path, "project.json.tmp")
	if err := os.WriteFile(tmpPath, raw, 0644); err != nil {
		return err
	}
	return os.Rename(tmpPath, filepath.Join(path, "project.json"))
}

// LoadProjectData reads project.json from a .former directory.
func LoadProjectData(path string) (*ProjectData, error) {
	raw, err := os.ReadFile(filepath.Join(path, "project.json"))
	if err != nil {
		return nil, err
	}
	var proj ProjectData
	if err := json.Unmarshal(raw, &proj); err != nil {
		return nil, err
	}
	return &proj, nil
}

// ProjectSubdir returns the mode-specific subdirectory within a .former project.
func ProjectSubdir(projectPath, mode string) string {
	return filepath.Join(projectPath, mode)
}

// ======== Recent Projects Tracking ========

// ListRecentProjects reads ~/former/recent.json and returns entries (newest first).
func ListRecentProjects() []RecentEntry {
	raw, err := os.ReadFile(formerRecentPath())
	if err != nil {
		return nil
	}
	var entries []RecentEntry
	json.Unmarshal(raw, &entries)

	// Filter out entries whose paths no longer exist
	var valid []RecentEntry
	for _, e := range entries {
		if _, err := os.Stat(filepath.Join(e.Path, "project.json")); err == nil {
			valid = append(valid, e)
		}
	}
	return valid
}

// AddRecentProject prepends a project to the recent list, deduplicates, caps at 20.
func AddRecentProject(path, name string) {
	entries := ListRecentProjects()
	entry := RecentEntry{Path: path, Name: name, LastOpened: time.Now()}

	var deduped []RecentEntry
	deduped = append(deduped, entry)
	for _, e := range entries {
		if e.Path != path {
			deduped = append(deduped, e)
		}
	}
	if len(deduped) > 20 {
		deduped = deduped[:20]
	}

	raw, _ := json.MarshalIndent(deduped, "", "  ")
	os.WriteFile(formerRecentPath(), raw, 0644)
}

// ======== Migration from Old Sessions/Profiles ========

// MigrateOldProjects converts ~/former/sessions/* and ~/former/profiles/* into .former projects.
// Non-destructive: renames old dirs to .migrated suffix.
func MigrateOldProjects() {
	for _, pair := range [][2]string{
		{formerSessionsDir(), "session"},
		{formerProfilesDir(), "profile"},
	} {
		dir := pair[0]
		if _, err := os.Stat(dir); os.IsNotExist(err) {
			continue
		}
		entries, err := os.ReadDir(dir)
		if err != nil {
			continue
		}
		migrated := 0
		for _, de := range entries {
			if !de.IsDir() {
				continue
			}
			oldPath := filepath.Join(dir, de.Name())
			jsonPath := filepath.Join(oldPath, "former.json")
			raw, err := os.ReadFile(jsonPath)
			if err != nil {
				continue
			}
			var inst InstanceData
			if json.Unmarshal(raw, &inst) != nil {
				continue
			}

			name := inst.ProjectName
			if inst.Name != "" {
				name = inst.Name
			}
			if name == "" {
				name = "Untitled"
			}
			safeName := sanitizeDirName(name)
			if safeName == "" {
				safeName = "untitled"
			}

			projPath := filepath.Join(formerProjectsDir(), safeName+".former")
			// Avoid overwriting
			if _, err := os.Stat(projPath); err == nil {
				projPath = filepath.Join(formerProjectsDir(), safeName+"-"+inst.ID[:8]+".former")
			}

			proj := &ProjectData{
				ID:        inst.ID,
				Name:      name,
				CreatedAt: inst.CreatedAt,
				Version:   1,
				Settings:  ProjectSettings{ShowGrid: true},
				Enclosure: &EnclosureData{
					GerberFiles:    inst.GerberFiles,
					DrillPath:      inst.DrillPath,
					NPTHPath:       inst.NPTHPath,
					EdgeCutsFile:   inst.EdgeCutsFile,
					CourtyardFile:  inst.CourtyardFile,
					SoldermaskFile: inst.SoldermaskFile,
					FabFile:        inst.FabFile,
					Config:         inst.Config,
					Exports:        inst.Exports,
					BoardW:         inst.BoardW,
					BoardH:         inst.BoardH,
					ProjectName:    inst.ProjectName,
					Cutouts:        inst.MigrateCutouts(),
				},
			}

			if err := os.MkdirAll(projPath, 0755); err != nil {
				continue
			}
			encDir := filepath.Join(projPath, "enclosure")
			os.MkdirAll(encDir, 0755)

			// Copy gerber files into enclosure subdir
			newGerberFiles := make(map[string]string)
			for origName := range inst.GerberFiles {
				srcPath := filepath.Join(oldPath, origName)
				dstPath := filepath.Join(encDir, origName)
				if CopyFile(srcPath, dstPath) == nil {
					newGerberFiles[origName] = origName
				}
			}
			proj.Enclosure.GerberFiles = newGerberFiles

			// Copy drill files
			if inst.DrillPath != "" {
				src := filepath.Join(oldPath, inst.DrillPath)
				dst := filepath.Join(encDir, inst.DrillPath)
				CopyFile(src, dst)
			}
			if inst.NPTHPath != "" {
				src := filepath.Join(oldPath, inst.NPTHPath)
				dst := filepath.Join(encDir, inst.NPTHPath)
				CopyFile(src, dst)
			}

			// Copy thumbnail
			thumbSrc := filepath.Join(oldPath, "thumbnail.png")
			thumbDst := filepath.Join(projPath, "thumbnail.png")
			CopyFile(thumbSrc, thumbDst)

			// Create other mode subdirs
			for _, sub := range []string{"stencil", "vectorwrap", "structural", "scanhelper"} {
				os.MkdirAll(filepath.Join(projPath, sub), 0755)
			}

			if SaveProject(projPath, proj) == nil {
				AddRecentProject(projPath, name)
				migrated++
			}
		}

		if migrated > 0 {
			migratedDir := dir + ".migrated"
			if err := os.Rename(dir, migratedDir); err != nil {
				log.Printf("migration: could not rename %s to %s: %v", dir, migratedDir, err)
			} else {
				log.Printf("Migrated %d old %ss from %s", migrated, pair[1], dir)
			}
		}
	}
}

// ======== Legacy Support (used during migration and by RestoreEnclosureProject) ========

// ProjectEntry represents a saved project on disk (legacy format)
type ProjectEntry struct {
	Path    string
	Type    string
	Data    InstanceData
	ModTime time.Time
}

// LoadLegacyProject reads former.json from a legacy project directory
func LoadLegacyProject(projectDir string) (*InstanceData, error) {
	raw, err := os.ReadFile(filepath.Join(projectDir, "former.json"))
	if err != nil {
		return nil, err
	}
	var inst InstanceData
	if err := json.Unmarshal(raw, &inst); err != nil {
		return nil, err
	}
	return &inst, nil
}

// RestoreEnclosureFromProject rebuilds an EnclosureSession from a .former project's enclosure data.
func RestoreEnclosureFromProject(projectPath string, encData *EnclosureData) (string, *EnclosureSession, error) {
	encDir := filepath.Join(projectPath, "enclosure")
	inst := &InstanceData{
		ID:             encData.ProjectName,
		GerberFiles:    encData.GerberFiles,
		DrillPath:      encData.DrillPath,
		NPTHPath:       encData.NPTHPath,
		EdgeCutsFile:   encData.EdgeCutsFile,
		CourtyardFile:  encData.CourtyardFile,
		SoldermaskFile: encData.SoldermaskFile,
		FabFile:        encData.FabFile,
		Config:         encData.Config,
		Exports:        encData.Exports,
		BoardW:         encData.BoardW,
		BoardH:         encData.BoardH,
		ProjectName:    encData.ProjectName,
	}
	return restoreSessionFromDir(inst, encDir)
}

// DeleteProject removes a project directory entirely
func DeleteProject(projectDir string) error {
	return os.RemoveAll(projectDir)
}

// SaveThumbnail saves a preview image to the project directory
func SaveThumbnail(projectDir string, img image.Image) error {
	f, err := os.Create(filepath.Join(projectDir, "thumbnail.png"))
	if err != nil {
		return err
	}
	defer f.Close()
	return png.Encode(f, img)
}

// ListProjectOutputFiles returns files in a mode's subdirectory.
func ListProjectOutputFiles(projectPath, mode string) []string {
	dir := filepath.Join(projectPath, mode)
	entries, err := os.ReadDir(dir)
	if err != nil {
		return nil
	}
	var files []string
	for _, e := range entries {
		if e.IsDir() {
			continue
		}
		files = append(files, filepath.Join(dir, e.Name()))
	}
	sort.Strings(files)
	return files
}

func sanitizeDirName(name string) string {
	name = strings.Map(func(r rune) rune {
		if r == '/' || r == '\\' || r == ':' || r == '*' || r == '?' || r == '"' || r == '<' || r == '>' || r == '|' {
			return '-'
		}
		return r
	}, name)
	name = strings.TrimSpace(name)
	if len(name) > 50 {
		name = name[:50]
	}
	return name
}