package main

import (
	"fmt"
	"io"
	"os"
	"os/exec"
	"path/filepath"
	"regexp"
	"strconv"
	"strings"
	"time"
)

func findAkaiutil() (string, error) {
	if env := os.Getenv("AKAIUTIL"); env != "" {
		if fi, err := os.Stat(env); err == nil && !fi.IsDir() {
			return env, nil
		}
	}

	candidates := []string{
		filepath.Join(filepath.Dir(os.Args[0]), "akaiutil"),
		filepath.Join(filepath.Dir(os.Args[0]), "third_party", "akaiutil", "akaiutil"),
		filepath.Join("third_party", "akaiutil", "akaiutil"),
		"akaiutil",
	}
	for _, p := range candidates {
		if fi, err := os.Stat(p); err == nil && !fi.IsDir() {
			return p, nil
		}
	}
	return "", fmt.Errorf("akaiutil not found — set AKAIUTIL env var or run: make akaiutil")
}

var runAkaiutil = func(isoPath, commands string) (string, error) {
	bin, err := findAkaiutil()
	if err != nil {
		return "", err
	}

	cmd := exec.Command(bin, "-r", isoPath)
	cmd.Stderr = nil

	stdin, err := cmd.StdinPipe()
	if err != nil {
		return "", fmt.Errorf("stdin pipe: %w", err)
	}
	stdout, err := cmd.StdoutPipe()
	if err != nil {
		return "", fmt.Errorf("stdout pipe: %w", err)
	}

	if err := cmd.Start(); err != nil {
		return "", fmt.Errorf("start akaiutil: %w", err)
	}

	stdin.Write([]byte(commands))
	stdin.Close()

	output, _ := io.ReadAll(stdout)
	cmd.Wait()

	return string(output), nil
}

type volInfo struct {
	Part string
	Name string
}

func listPartitions(isoPath string) ([]string, error) {
	out, err := runAkaiutil(isoPath, "df\nq\n")
	if err != nil {
		return nil, err
	}

	re := regexp.MustCompile(`^\s+([A-Z])\s+`)
	var parts []string
	for _, line := range strings.Split(out, "\n") {
		if m := re.FindStringSubmatch(line); m != nil {
			parts = append(parts, m[1])
		}
	}
	if len(parts) == 0 {
		return []string{"A"}, nil
	}
	return parts, nil
}

func listVolumes(isoPath string, partitions []string) ([]volInfo, error) {
	var cmds strings.Builder
	for _, p := range partitions {
		fmt.Fprintf(&cmds, "cd /disk0/%s\n", p)
		fmt.Fprintf(&cmds, "dir\n")
	}
	cmds.WriteString("q\n")

	out, err := runAkaiutil(isoPath, cmds.String())
	if err != nil {
		return nil, err
	}

	rePrompt := regexp.MustCompile(`/disk0/([A-Z])\s*>`)
	reEntry := regexp.MustCompile(`^\s+\d+\s+(.+?)\s+-\s+`)

	var vols []volInfo
	currentPart := ""

	for _, line := range strings.Split(out, "\n") {
		if m := rePrompt.FindStringSubmatch(line); m != nil {
			currentPart = m[1]
			continue
		}
		if m := reEntry.FindStringSubmatch(line); m != nil {
			name := strings.TrimRight(m[1], " ")
			if currentPart != "" && name != "" {
				vols = append(vols, volInfo{Part: currentPart, Name: name})
			}
		}
	}
	return vols, nil
}

func runExtraction(isoPath, baseDir string, vols []volInfo) (int, error) {
	var cmds strings.Builder
	for _, v := range vols {
		safe := sanitiseISOName(v.Name)
		if safe == "" {
			safe = "volume"
		}
		volDir := filepath.Join(baseDir, safe)
		os.MkdirAll(volDir, 0755)

		nav := strings.ReplaceAll(v.Name, " ", "_")
		fmt.Fprintf(&cmds, "lcd %s\n", volDir)
		fmt.Fprintf(&cmds, "cd /disk0/%s/%s\n", v.Part, nav)
		fmt.Fprintf(&cmds, "sample2wavall\n")
	}
	fmt.Fprintf(&cmds, "lcd /\nq\n")

	out, err := runAkaiutil(isoPath, cmds.String())
	if err != nil {
		return 0, err
	}

	re := regexp.MustCompile(`exported\s+(\d+)\s+file`)
	total := 0
	for _, line := range strings.Split(out, "\n") {
		if m := re.FindStringSubmatch(line); m != nil {
			n, _ := strconv.Atoi(m[1])
			total += n
		}
	}
	return total, nil
}

func extractWAVs(isoPath, outDir string) (int, error) {
	parts, err := listPartitions(isoPath)
	if err != nil {
		return 0, fmt.Errorf("enumerate partitions: %w", err)
	}

	vols, err := listVolumes(isoPath, parts)
	if err != nil {
		return 0, fmt.Errorf("enumerate volumes: %w", err)
	}
	if len(vols) == 0 {
		return 0, nil
	}

	isoBase := sanitiseISOName(filepath.Base(isoPath))
	baseDir := filepath.Join(outDir, isoBase)
	os.MkdirAll(baseDir, 0755)

	return runExtraction(isoPath, baseDir, vols)
}

func extractISO(isoPath, outDir string) (string, error) {
	isoOutDir := filepath.Join(outDir, sanitiseISOName(filepath.Base(isoPath)))

	if fi, err := os.Stat(isoOutDir); err == nil && fi.IsDir() {
		var wavCount int
		filepath.WalkDir(isoOutDir, func(p string, d os.DirEntry, err error) error {
			if err == nil && !d.IsDir() && strings.HasSuffix(strings.ToLower(d.Name()), ".wav") {
				wavCount++
			}
			return nil
		})
		if wavCount > 0 {
			return fmt.Sprintf("skipped (%d WAVs exist)", wavCount), nil
		}
	}

	start := time.Now()
	total, err := extractWAVs(isoPath, outDir)
	elapsed := time.Since(start).Round(time.Second)
	if err != nil {
		return "", err
	}
	return fmt.Sprintf("Total WAV files: %d (%s)", total, elapsed), nil
}