package main

import (
	"bytes"
	"crypto/sha512"
	"encoding/hex"
	"encoding/json"
	"fmt"
	"io"
	"math/rand"
	"net/http"
	"net/url"
	"os"
	"os/exec"
	"path/filepath"

	"git.milar.in/milarin/envvars/v2"
	"git.milar.in/milarin/slices"
	"github.com/gorilla/mux"
)

var (
	HttpIntf    = envvars.String("HTTP_INTERFACE", "")
	HttpPort    = envvars.Uint16("HTTP_PORT", 80)
	LibraryPath = envvars.String("LIBRARY_PATH", "/music")
)

func main() {
	if _, err := exec.LookPath("ffmpeg"); err != nil {
		panic("ffmpeg not found in PATH")
	}

	r := mux.NewRouter()

	r.HandleFunc("/all/", GetAllHandler).Methods("GET")
	r.HandleFunc("/all/hash/", GetAllHashHandler).Methods("GET")
	r.HandleFunc("/playlist-names/", GetPlaylistNamesHandler).Methods("GET")
	r.HandleFunc("/playlist/{playlist}/", GetPlaylistHandler).Methods("GET")
	r.HandleFunc("/file/{file}/", GetFileHandler).Methods("GET")
	r.HandleFunc("/file/{file}/hash/", GetFileHashHandler).Methods("GET")
	r.HandleFunc("/file/{file}/format/{format}/", GetEncodeFileHandler).Methods("GET")
	r.HandleFunc("/file/", GetAllFilesHandler).Methods("GET")

	fmt.Printf("Starting music server on port %d\n", HttpPort)
	if err := http.ListenAndServe(fmt.Sprintf("%s:%d", HttpIntf, HttpPort), r); err != nil {
		panic(err)
	}
}

func GetAllHashHandler(w http.ResponseWriter, r *http.Request) {
	playlists, err := GetAllPlaylists()
	if err != nil {
		InternalServerError(w, err)
		return
	}

	b := &bytes.Buffer{}
	if err := json.NewEncoder(b).Encode(playlists); err != nil {
		InternalServerError(w, err)
		return
	}

	hash := sha512.Sum512(b.Bytes())
	if _, err := fmt.Fprint(w, hex.EncodeToString(hash[:])); err != nil {
		InternalServerError(w, err)
		return
	}
}

func GetAllHandler(w http.ResponseWriter, r *http.Request) {
	playlists, err := GetAllPlaylists()
	if err != nil {
		InternalServerError(w, err)
		return
	}

	w.Header().Add("Content-Type", "application/json")
	if err := json.NewEncoder(w).Encode(playlists); err != nil {
		InternalServerError(w, err)
		return
	}
}

func GetFileHandler(w http.ResponseWriter, r *http.Request) {
	fileName, err := url.QueryUnescape(mux.Vars(r)["file"])
	if err != nil {
		InternalServerError(w, err)
		return
	}

	http.ServeFile(w, r, filepath.Join(LibraryPath, ".songs", fileName))
}

func GetFileHashHandler(w http.ResponseWriter, r *http.Request) {
	fileName, err := url.QueryUnescape(mux.Vars(r)["file"])
	if err != nil {
		InternalServerError(w, err)
		return
	}

	filePath := filepath.Join(LibraryPath, ".songs", fileName)

	f, err := os.Open(filePath)
	if err != nil {
		InternalServerError(w, err)
		return
	}
	defer f.Close()

	hasher := sha512.New()
	if _, err := io.Copy(hasher, f); err != nil {
		InternalServerError(w, err)
		return
	}

	if _, err := fmt.Fprint(w, hex.EncodeToString(hasher.Sum(nil))); err != nil {
		InternalServerError(w, err)
		return
	}
}

func GetPlaylistHandler(w http.ResponseWriter, r *http.Request) {
	playlistName := mux.Vars(r)["playlist"]

	songs, err := GetSongsByPlaylist(playlistName)
	if err != nil {
		InternalServerError(w, err)
		return
	}

	playlist := Playlist{
		Name:  playlistName,
		Songs: songs,
	}

	w.Header().Add("Content-Type", "application/json")
	if err := json.NewEncoder(w).Encode(playlist); err != nil {
		InternalServerError(w, err)
		return
	}
}

func GetPlaylistNamesHandler(w http.ResponseWriter, r *http.Request) {
	playlistNames, err := GetAllPlaylistNames()
	if err != nil {
		InternalServerError(w, err)
		return
	}

	w.Header().Add("Content-Type", "application/json")
	if err := json.NewEncoder(w).Encode(playlistNames); err != nil {
		InternalServerError(w, err)
		return
	}
}

func GetAllFilesHandler(w http.ResponseWriter, r *http.Request) {
	fileDirectory := filepath.Join(LibraryPath, ".songs")

	entries, err := os.ReadDir(fileDirectory)
	if err != nil {
		InternalServerError(w, err)
		return
	}

	files := slices.Filter(entries, IsRegular)
	fileNames := slices.Map(files, FsEntry2Name)

	w.Header().Add("Content-Type", "application/json")
	if err := json.NewEncoder(w).Encode(fileNames); err != nil {
		InternalServerError(w, err)
		return
	}
}

func GetEncodeFileHandler(w http.ResponseWriter, r *http.Request) {
	vars := mux.Vars(r)
	format := vars["format"]
	fileName, err := url.QueryUnescape(vars["file"])
	if err != nil {
		InternalServerError(w, err)
		return
	}

	inputFilePath := filepath.Join(LibraryPath, ".songs", fileName)
	outputFilePath := filepath.Join(os.TempDir(), fmt.Sprintf("%d.%s", rand.Int(), format))
	defer os.Remove(outputFilePath)

	fmt.Printf("encode file to %s: '%s' -> '%s'\n", format, inputFilePath, outputFilePath)

	cmd := exec.Command("ffmpeg", "-i", inputFilePath, "-vn", outputFilePath)
	if err := cmd.Start(); err != nil {
		InternalServerError(w, err)
		return
	}
	if err := cmd.Wait(); err != nil {
		InternalServerError(w, err)
		return
	}

	http.ServeFile(w, r, outputFilePath)
}