package editor

import (
	"sort"
	"strings"
	"time"

	"pad/internal/browser"
	"pad/internal/io/pool/mock"
)

// populateMockFileSystem seeds the mock filesystem with sample data for testing.
// Creates a realistic directory structure with subdirectories, various file types,
// and varied sizes/dates to exercise the browser functionality.
func populateMockFileSystem(fs *mock.FileSystem) {
	baseTime := time.Date(2026, 5, 15, 10, 0, 0, 0, time.UTC)

	// --- Root directories ---
	dirs := []string{
		"/Documents",
		"/Pictures",
		"/Music",
		"/Downloads",
		"/Projects",
		"/Projects/pad",
		"/Projects/goplus",
		"/Documents/Work",
		"/Documents/Personal",
		"/Pictures/Vacation",
	}
	for i, d := range dirs {
		fs.AddDir(d, baseTime.AddDate(0, 0, -i))
	}

	// --- Root files ---
	rootFiles := []struct {
		name string
		size int64
		days int
	}{
		{"README.md", 2048, -30},
		{"config.yaml", 512, -60},
		{"notes.txt", 1024, -15},
		{"setup.log", 4096, -7},
		{".gitignore", 128, -90},
	}
	for _, f := range rootFiles {
		fs.AddFile("/"+f.name, make([]byte, f.size), baseTime.AddDate(0, 0, f.days))
	}

	// --- Documents/Work files ---
	workFiles := []struct {
		name string
		size int64
		days int
	}{
		{"Q1_Report.docx", 524288, -45},
		{"Q2_Report.docx", 614400, -14},
		{"Budget_2026.xlsx", 262144, -30},
		{"Meeting_Notes.txt", 8192, -1},
		{"Presentation.pptx", 1048576, -21},
	}
	for _, f := range workFiles {
		fs.AddFile("/Documents/Work/"+f.name, make([]byte, f.size), baseTime.AddDate(0, 0, f.days))
	}

	// --- Documents/Personal files ---
	personalFiles := []struct {
		name string
		size int64
		days int
	}{
		{"Resume.pdf", 32768, -60},
		{"Tax_Return_2025.pdf", 131072, -90},
		{"Recipe_Collection.txt", 4096, -120},
		{"Letter_to_Friend.txt", 2048, -5},
	}
	for _, f := range personalFiles {
		fs.AddFile("/Documents/Personal/"+f.name, make([]byte, f.size), baseTime.AddDate(0, 0, f.days))
	}

	// --- Projects/pad source files ---
	padFiles := []struct {
		name string
		size int64
		days int
	}{
		{"main.go", 3072, -2},
		{"state.go", 4096, -2},
		{"logic.go", 5120, -1},
		{"browser.go", 2048, -7},
		{"types.go", 1536, -7},
		{"index.go", 3584, -7},
		{"layout.go", 2560, -5},
		{"handlers.go", 1024, -3},
		{"go.mod", 256, -30},
		{"go.sum", 512, -30},
	}
	for _, f := range padFiles {
		fs.AddFile("/Projects/pad/"+f.name, make([]byte, f.size), baseTime.AddDate(0, 0, f.days))
	}

	// --- Pictures/Vacation files ---
	vacationFiles := []struct {
		name string
		size int64
		days int
	}{
		{"IMG_0001.jpg", 3145728, -180},
		{"IMG_0002.jpg", 2621440, -180},
		{"IMG_0003.jpg", 4194304, -179},
		{"IMG_0004.jpg", 3670016, -179},
		{"IMG_0005.jpg", 2097152, -178},
	}
	for _, f := range vacationFiles {
		fs.AddFile("/Pictures/Vacation/"+f.name, make([]byte, f.size), baseTime.AddDate(0, 0, f.days))
	}

	// --- Downloads files ---
	downloads := []struct {
		name string
		size int64
		days int
	}{
		{"installer.dmg", 104857600, -10},
		{"archive.tar.gz", 52428800, -20},
		{"patch.diff", 8192, -3},
	}
	for _, f := range downloads {
		fs.AddFile("/Downloads/"+f.name, make([]byte, f.size), baseTime.AddDate(0, 0, f.days))
	}
}

// sortModeKey converts a browser.SortMode to its JSON key string.
func sortModeKey(mode browser.SortMode) string {
	switch mode {
	case 0: // SortModeNameAsc
		return "name_asc"
	case 1: // SortModeNameDesc
		return "name_desc"
	case 2: // SortModeDateAsc
		return "date_asc"
	case 3: // SortModeDateDesc
		return "date_desc"
	default:
		return ""
	}
}

// modeCount returns the total number of sort modes.
func modeCount() int {
	return 4
}

// buildBrowserIndex converts mock DirEntry results into a browser.DirectoryIndex
// with pre-computed position maps for all sort modes.
func buildBrowserIndex(entries []mock.DirEntry) *browser.DirectoryIndex {
	var browserEntries []browser.Entry
	for _, e := range entries {
		info, err := e.Info()
		if err != nil {
			continue
		}
		browserEntries = append(browserEntries, browser.Entry{
			Path:    e.Name(),
			Name:    e.Name(),
			Size:    info.Size(),
			ModTime: info.ModTime(),
			IsDir:   info.IsDir(),
		})
	}

	// Build position maps for all sort modes
	sortOrders := make(map[string][]int)
	for mode := browser.SortMode(0); mode < browser.SortMode(modeCount()); mode++ {
		key := sortModeKey(mode)
		if key != "" {
			sortOrders[key] = buildPositionMap(browserEntries, mode)
		}
	}

	return &browser.DirectoryIndex{
		Path:       "/",
		EntryCount: len(browserEntries),
		Entries:    browserEntries,
		SortOrders: sortOrders,
	}
}

// buildPositionMap creates a sorted index → raw index mapping.
func buildPositionMap(entries []browser.Entry, mode browser.SortMode) []int {
	n := len(entries)
	indices := make([]int, n)
	for i := range indices {
		indices[i] = i
	}

	// Sort indices based on entry comparison
	cmp := comparator(mode)
	sort.SliceStable(indices, func(i, j int) bool {
		a, b := entries[indices[i]], entries[indices[j]]
		return cmp(a, b) < 0
	})

	return indices
}

// comparator returns a comparison function for the given SortMode.
// Returns negative if a < b, zero if equal, positive if a > b.
func comparator(mode browser.SortMode) func(a, b browser.Entry) int {
	switch mode {
	case 0: // SortModeNameAsc
		return func(a, b browser.Entry) int {
			if c := strings.Compare(strings.ToLower(a.Name), strings.ToLower(b.Name)); c != 0 {
				return c
			}
			return strings.Compare(a.Name, b.Name)
		}
	case 1: // SortModeNameDesc
		return func(a, b browser.Entry) int {
			if c := strings.Compare(strings.ToLower(b.Name), strings.ToLower(a.Name)); c != 0 {
				return c
			}
			return strings.Compare(b.Name, a.Name)
		}
	case 2: // SortModeDateAsc
		return func(a, b browser.Entry) int {
			if c := a.ModTime.Compare(b.ModTime); c != 0 {
				return c
			}
			return strings.Compare(strings.ToLower(a.Name), strings.ToLower(b.Name))
		}
	case 3: // SortModeDateDesc
		return func(a, b browser.Entry) int {
			if c := b.ModTime.Compare(a.ModTime); c != 0 {
				return c
			}
			return strings.Compare(strings.ToLower(a.Name), strings.ToLower(b.Name))
		}
	default:
		return func(a, b browser.Entry) int { return 0 }
	}
}