package cmd

import (
	"bufio"
	"fmt"
	"os"
	"path/filepath"
	"strings"
	"time"

	"github.com/fatih/color"
	"github.com/spf13/cobra"
	"github.com/torrentclaw/torrentclaw-cli/internal/agent"
	"github.com/torrentclaw/torrentclaw-cli/internal/config"
	"github.com/torrentclaw/torrentclaw-cli/internal/ui"
)

func newCleanCmd() *cobra.Command {
	var (
		dryRun bool
		all    bool
		yes    bool
	)

	cmd := &cobra.Command{
		Use:   "clean",
		Short: "Remove temporary files, logs, and cached data",
		Long: `Remove temporary files, logs, resume data, and other artifacts generated by unarr.

Shows what will be removed and asks for confirmation before deleting.

By default, cleans:
  - Log files (unarr.log, unarr.err.log)
  - Daemon state file (daemon.state.json)
  - Stale usenet resume files older than 7 days (.progress, .nzb cache)
  - Stream temp directory (/tmp/unarr-stream/)
  - Upgrade temp files (/tmp/unarr-download-*.tmp)
  - Stale atomic-write temp files (.tmp)

Recent usenet resume files (< 7 days) are kept to preserve download
progress for paused or interrupted downloads.

With --all, also removes:
  - ALL usenet resume files (including recent ones)
  - The entire data directory (~/.local/share/unarr/)

Never removes:
  - Configuration file (config.toml)
  - Downloaded media files
  - Partial torrent or debrid downloads (stored in your download dir)`,
		Example: `  unarr clean            # Show files and confirm before removing
  unarr clean --dry-run  # Show what would be removed (no prompt)
  unarr clean --yes      # Skip confirmation
  unarr clean --all      # Also remove the data directory`,
		RunE: func(cmd *cobra.Command, args []string) error {
			return runClean(dryRun, all, yes)
		},
	}

	cmd.Flags().BoolVar(&dryRun, "dry-run", false, "show what would be removed without deleting")
	cmd.Flags().BoolVar(&all, "all", false, "also remove the entire data directory")
	cmd.Flags().BoolVarP(&yes, "yes", "y", false, "skip confirmation prompt")

	return cmd
}

type cleanTarget struct {
	path        string
	description string
	isDir       bool
	isGlob      bool
}

// foundEntry represents a file or directory found during scanning.
type foundEntry struct {
	path  string
	desc  string
	size  int64
	isDir bool
}

func runClean(dryRun, all, yes bool) error {
	bold := color.New(color.Bold)
	green := color.New(color.FgGreen)
	yellow := color.New(color.FgYellow)
	dim := color.New(color.FgHiBlack)

	// Check if daemon is running
	if state := agent.ReadState(); state != nil && state.PID > 0 {
		if agent.IsProcessAlive(state.PID) {
			return fmt.Errorf("daemon is running (PID %d) — stop it first with Ctrl+C or 'unarr stop'", state.PID)
		}
	}

	dataDir := config.DataDir()
	tmpDir := os.TempDir()

	// With --all, remove the entire data directory (includes logs, state, resume).
	// Without --all, target individual files + stale resume files only.
	var targets []cleanTarget
	if all {
		targets = []cleanTarget{
			{dataDir, "data directory", true, false},
		}
	} else {
		targets = []cleanTarget{
			{filepath.Join(dataDir, "unarr.log"), "daemon log", false, false},
			{filepath.Join(dataDir, "unarr.err.log"), "daemon error log", false, false},
			{filepath.Join(dataDir, "daemon.state.json"), "daemon state", false, false},
			{filepath.Join(dataDir, "daemon.state.json.tmp"), "daemon state temp", false, false},
			// Resume files handled separately below (stale only)
		}
	}

	// Temp targets apply regardless of --all
	targets = append(targets,
		cleanTarget{filepath.Join(tmpDir, "unarr-stream"), "stream temp data", true, false},
		cleanTarget{filepath.Join(tmpDir, "unarr-download-*.tmp"), "upgrade temp files", false, true},
		cleanTarget{config.FilePath() + ".tmp", "config temp", false, false},
	)

	// Phase 1: Scan and collect what exists
	var found []foundEntry
	var totalFiles int
	var totalBytes int64

	for _, t := range targets {
		if t.isGlob {
			matches, _ := filepath.Glob(t.path)
			for _, m := range matches {
				size := fileSize(m)
				totalFiles++
				totalBytes += size
				found = append(found, foundEntry{m, t.description, size, false})
			}
			continue
		}

		info, err := os.Stat(t.path)
		if err != nil {
			continue
		}

		if t.isDir {
			files, bytes := dirStats(t.path)
			if files == 0 {
				continue
			}
			totalFiles += files
			totalBytes += bytes
			found = append(found, foundEntry{
				path:  t.path + "/",
				desc:  fmt.Sprintf("%s (%d files)", t.description, files),
				size:  bytes,
				isDir: true,
			})
		} else {
			totalFiles++
			totalBytes += info.Size()
			found = append(found, foundEntry{t.path, t.description, info.Size(), false})
		}
	}

	// Resume files: only scan individually when NOT --all (--all already includes them via dataDir)
	var resumeSkipped int
	if !all {
		resumeDir := filepath.Join(dataDir, "resume")
		var resumeFound []foundEntry
		resumeFound, resumeSkipped = scanResumeFiles(resumeDir, false)
		for _, e := range resumeFound {
			totalFiles++
			totalBytes += e.size
			found = append(found, e)
		}
	}

	// Phase 2: Show what was found
	fmt.Println()
	bold.Println("  unarr clean")
	fmt.Println()

	if totalFiles == 0 {
		dim.Println("  Nothing to clean.")
		fmt.Println()
		return nil
	}

	fmt.Println("  Files to remove:")
	fmt.Println()
	for _, e := range found {
		display := shortenHome(e.path)
		fmt.Printf("    %s ", display)
		dim.Printf("(%s, %s)\n", e.desc, ui.FormatBytes(e.size))
	}
	fmt.Println()
	bold.Printf("  Total: %d file(s), %s\n", totalFiles, ui.FormatBytes(totalBytes))
	if resumeSkipped > 0 {
		dim.Printf("  Kept %d recent resume file(s) (< 7 days) — use --all to include\n", resumeSkipped)
	}
	fmt.Println()

	// Phase 3: Dry run stops here
	if dryRun {
		yellow.Println("  Dry run — nothing will be deleted.")
		fmt.Println()
		return nil
	}

	// Phase 4: Ask for confirmation (unless --yes)
	if !yes {
		fmt.Print("  Proceed? [y/N] ")
		scanner := bufio.NewScanner(os.Stdin)
		scanner.Scan()
		answer := strings.TrimSpace(strings.ToLower(scanner.Text()))
		if answer != "y" && answer != "yes" {
			fmt.Println()
			yellow.Println("  Aborted.")
			fmt.Println()
			return nil
		}
		fmt.Println()
	}

	// Phase 5: Delete
	for _, e := range found {
		if e.isDir {
			os.RemoveAll(strings.TrimSuffix(e.path, "/"))
		} else {
			os.Remove(e.path)
		}
		display := shortenHome(e.path)
		green.Print("  ✓ ")
		fmt.Println(display)
	}

	fmt.Println()
	green.Printf("  ✓ Removed %d file(s), %s freed\n", totalFiles, ui.FormatBytes(totalBytes))
	fmt.Println()

	return nil
}

// scanResumeFiles scans the resume directory for cleanable files.
// If all is true, returns all files. Otherwise only stale files (>7 days).
func scanResumeFiles(resumeDir string, all bool) (found []foundEntry, skipped int) {
	entries, err := os.ReadDir(resumeDir)
	if err != nil {
		return nil, 0
	}

	const staleAge = 7 * 24 * time.Hour

	for _, e := range entries {
		if e.IsDir() {
			continue
		}
		info, err := e.Info()
		if err != nil {
			continue
		}

		isStale := time.Since(info.ModTime()) > staleAge
		if !all && !isStale {
			skipped++
			continue
		}

		path := filepath.Join(resumeDir, e.Name())
		desc := "stale resume file"
		if all && !isStale {
			desc = "resume file"
		}
		found = append(found, foundEntry{path, desc, info.Size(), false})
	}
	return found, skipped
}

func shortenHome(path string) string {
	home, _ := os.UserHomeDir()
	if home != "" {
		return strings.Replace(path, home, "~", 1)
	}
	return path
}

func dirStats(dir string) (int, int64) {
	var files int
	var bytes int64
	filepath.Walk(dir, func(path string, info os.FileInfo, err error) error {
		if err != nil {
			return nil
		}
		if !info.IsDir() {
			files++
			bytes += info.Size()
		}
		return nil
	})
	return files, bytes
}

func fileSize(path string) int64 {
	info, err := os.Stat(path)
	if err != nil {
		return 0
	}
	return info.Size()
}

// CleanableBytes calculates the total size of files that would be safe to clean
// right now. Called from the daemon heartbeat to report cleanable space.
// Excludes daemon.state.json (actively written while daemon runs) and
// recent resume files (< 7 days, needed for download resume).
func CleanableBytes() int64 {
	dataDir := config.DataDir()
	tmpDir := os.TempDir()
	var total int64

	// Logs
	total += fileSize(filepath.Join(dataDir, "unarr.log"))
	total += fileSize(filepath.Join(dataDir, "unarr.err.log"))

	// Stale resume files only (>7 days)
	resumeFound, _ := scanResumeFiles(filepath.Join(dataDir, "resume"), false)
	for _, e := range resumeFound {
		total += e.size
	}

	// Stream temp
	_, streamBytes := dirStats(filepath.Join(tmpDir, "unarr-stream"))
	total += streamBytes

	// Upgrade temp files
	matches, _ := filepath.Glob(filepath.Join(tmpDir, "unarr-download-*.tmp"))
	for _, m := range matches {
		total += fileSize(m)
	}

	// Config temp
	total += fileSize(config.FilePath() + ".tmp")

	return total
}