package download_test

import (
	"crypto/md5"
	"fmt"
	"net/http"
	"net/http/httptest"
	"os"
	"path/filepath"
	"testing"

	"gorm.io/driver/sqlite"
	"gorm.io/gorm"
	"rhemawavetech.com/rhemawave/internal/db"
	"rhemawavetech.com/rhemawave/internal/download"
)

func md5Hex(data []byte) string {
	return fmt.Sprintf("%x", md5.Sum(data))
}

// TestDownloadFileHashChanged verifies that when the server manifest reports a
// new MD5 for an existing local file, the old file is removed, the new version
// is downloaded, and the database record is updated with the new hash.
func TestDownloadFileHashChanged(t *testing.T) {
	audioDir := t.TempDir()
	dbDir := t.TempDir()

	gdb, err := gorm.Open(sqlite.Open(filepath.Join(dbDir, "test.db")), &gorm.Config{})
	if err != nil {
		t.Fatal(err)
	}
	sqlDB, err := gdb.DB()
	if err != nil {
		t.Fatal(err)
	}
	sqlDB.SetMaxOpenConns(1)
	sqlDB.SetMaxIdleConns(1)

	if err := gdb.AutoMigrate(&db.AudioTrack{}); err != nil {
		t.Fatal(err)
	}

	oldContent := []byte("this is the OLD version of the audio file")
	oldMD5 := md5Hex(oldContent)
	newContent := []byte("this is the NEW version of the audio file")
	newMD5 := md5Hex(newContent)

	track := db.AudioTrack{
		Filename:          "174Hz.wav",
		Name:              "174 Hz",
		AssignedFrequency: 174,
		MD5:               oldMD5,
		Selected:          true,
		Order:             2,
	}
	if err := gdb.Create(&track).Error; err != nil {
		t.Fatal(err)
	}

	oldPath := filepath.Join(audioDir, "174Hz.wav")
	if err := os.WriteFile(oldPath, oldContent, 0644); err != nil {
		t.Fatal(err)
	}

	server := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		switch r.URL.Path {
		case "/checksums.md5":
			w.WriteHeader(http.StatusOK)
			fmt.Fprintf(w, "%s  174Hz.wav\n", newMD5)
		case "/174Hz.wav":
			w.WriteHeader(http.StatusOK)
			w.Write(newContent)
		default:
			http.NotFound(w, r)
		}
	}))
	defer server.Close()

	progress := make(chan download.DownloadStatus, 100)
	done := make(chan struct{})
	go func() {
		download.DownloadAudioFiles(progress, gdb, audioDir, server.URL+"/")
		close(done)
	}()
	for range progress {
	}
	<-done

	newPath := filepath.Join(audioDir, "174Hz.wav")
	gotContent, err := os.ReadFile(newPath)
	if err != nil {
		t.Fatalf("reading new file: %v", err)
	}
	if string(gotContent) != string(newContent) {
		t.Errorf("new file content = %q, want %q", string(gotContent), string(newContent))
	}

	var updated db.AudioTrack
	if err := gdb.First(&updated, track.ID).Error; err != nil {
		t.Fatalf("fetching updated track: %v", err)
	}
	if updated.MD5 != newMD5 {
		t.Errorf("DB MD5 = %q, want %q", updated.MD5, newMD5)
	}
}

// TestDownloadOrphanRemoval verifies that files and DB records not in the
// manifest are removed.
func TestDownloadOrphanRemoval(t *testing.T) {
	audioDir := t.TempDir()
	dbDir := t.TempDir()

	gdb, err := gorm.Open(sqlite.Open(filepath.Join(dbDir, "test.db")), &gorm.Config{})
	if err != nil {
		t.Fatal(err)
	}
	sqlDB, err := gdb.DB()
	if err != nil {
		t.Fatal(err)
	}
	sqlDB.SetMaxOpenConns(1)
	sqlDB.SetMaxIdleConns(1)

	if err := gdb.AutoMigrate(&db.AudioTrack{}); err != nil {
		t.Fatal(err)
	}

	orphanPath := filepath.Join(audioDir, "orphan.wav")
	if err := os.WriteFile(orphanPath, []byte("orphan"), 0644); err != nil {
		t.Fatal(err)
	}

	gdb.Create(&db.AudioTrack{Filename: "ghost.wav", Name: "Ghost Track", Order: 99})

	keptContent := []byte("kept file")
	keptMD5 := md5Hex(keptContent)
	keptPath := filepath.Join(audioDir, "kept.wav")
	if err := os.WriteFile(keptPath, keptContent, 0644); err != nil {
		t.Fatal(err)
	}

	server := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		switch r.URL.Path {
		case "/checksums.md5":
			w.WriteHeader(http.StatusOK)
			fmt.Fprintf(w, "%s  kept.wav\n", keptMD5)
		case "/kept.wav":
			w.WriteHeader(http.StatusOK)
			w.Write(keptContent)
		default:
			http.NotFound(w, r)
		}
	}))
	defer server.Close()

	progress := make(chan download.DownloadStatus, 100)
	done := make(chan struct{})
	go func() {
		download.DownloadAudioFiles(progress, gdb, audioDir, server.URL+"/")
		close(done)
	}()
	for range progress {
	}
	<-done

	if _, err := os.Stat(orphanPath); !os.IsNotExist(err) {
		t.Errorf("orphan file %s should have been removed", orphanPath)
	}

	var count int64
	gdb.Model(&db.AudioTrack{}).Where("filename = ?", "ghost.wav").Count(&count)
	if count != 0 {
		t.Errorf("orphan DB record ghost.wav should have been deleted, count=%d", count)
	}

	if _, err := os.Stat(keptPath); os.IsNotExist(err) {
		t.Errorf("kept file %s should still exist after download", keptPath)
	}
}