package api

import (
	"crypto/subtle"
	"fmt"
	"io"
	"net/http"
	"os"
	"path/filepath"
	"regexp"
	"strings"

	"github.com/ponzischeme89/memby/server/internal/appupdate"
)

const maxReleaseSize = 250 << 20

var (
	releaseVersionPattern  = regexp.MustCompile(`^\d+\.\d+\.\d+$`)
	releaseFilenamePattern = regexp.MustCompile(`^memby-\d+\.\d+\.\d+\.apk$`)
)

// releasePublishAuth is deliberately separate from adminAuth: CI can publish an APK but
// cannot take the service offline, force an update, or read household analytics.
func (s *Server) releasePublishAuth(h http.HandlerFunc) http.Handler {
	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		if s.cfg.ReleasePublishToken == "" {
			http.NotFound(w, r)
			return
		}
		presented := strings.TrimSpace(strings.TrimPrefix(r.Header.Get("Authorization"), "Bearer "))
		if subtle.ConstantTimeCompare([]byte(presented), []byte(s.cfg.ReleasePublishToken)) != 1 {
			writeError(w, http.StatusUnauthorized, "invalid release token")
			return
		}
		h(w, r)
	})
}

// handleReleasePublish accepts the signed APK produced by Gitea Actions, persists it,
// and atomically makes it the version offered to TVs.
func (s *Server) handleReleasePublish(w http.ResponseWriter, r *http.Request) {
	r.Body = http.MaxBytesReader(w, r.Body, maxReleaseSize)
	if err := r.ParseMultipartForm(16 << 20); err != nil {
		writeError(w, http.StatusBadRequest, "invalid release upload")
		return
	}

	version := strings.TrimSpace(r.FormValue("version"))
	if !releaseVersionPattern.MatchString(version) {
		writeError(w, http.StatusBadRequest, "version must look like 0.1.54")
		return
	}

	current := s.updatePolicy.get()
	if current.LatestVersion != "" &&
		appupdate.CompareVersions(version, current.LatestVersion) < 0 {
		writeError(w, http.StatusConflict, "refusing to publish an older version")
		return
	}

	source, _, err := r.FormFile("apk")
	if err != nil {
		writeError(w, http.StatusBadRequest, "signed APK is required")
		return
	}
	defer source.Close()

	if err := os.MkdirAll(s.cfg.ReleaseDir, 0o750); err != nil {
		s.log.Error("release directory unavailable", "error", err)
		writeError(w, http.StatusInternalServerError, "release storage unavailable")
		return
	}
	temp, err := os.CreateTemp(s.cfg.ReleaseDir, ".memby-upload-*")
	if err != nil {
		s.log.Error("release temp file failed", "error", err)
		writeError(w, http.StatusInternalServerError, "release storage unavailable")
		return
	}
	tempName := temp.Name()
	defer os.Remove(tempName)

	written, copyErr := io.Copy(temp, source)
	closeErr := temp.Close()
	if copyErr != nil || closeErr != nil || written < 4 {
		writeError(w, http.StatusBadRequest, "could not store APK")
		return
	}

	// APKs are ZIP archives. This catches accidentally uploaded logs or HTML error pages
	// before they become an update every TV is invited to install.
	stored, err := os.Open(tempName)
	if err != nil {
		writeError(w, http.StatusInternalServerError, "could not verify APK")
		return
	}
	var magic [4]byte
	_, readErr := io.ReadFull(stored, magic[:])
	stored.Close()
	if readErr != nil || string(magic[:2]) != "PK" {
		writeError(w, http.StatusBadRequest, "uploaded file is not an APK")
		return
	}

	filename := fmt.Sprintf("memby-%s.apk", version)
	destination := filepath.Join(s.cfg.ReleaseDir, filename)
	if err := os.Rename(tempName, destination); err != nil {
		s.log.Error("release publish rename failed", "error", err)
		writeError(w, http.StatusInternalServerError, "could not publish APK")
		return
	}
	if err := os.Chmod(destination, 0o640); err != nil {
		s.log.Warn("release permissions could not be tightened", "error", err)
	}

	policy := appupdate.Policy{
		Enabled:        true,
		LatestVersion:  version,
		MinimumVersion: current.MinimumVersion,
		DownloadURL:    s.cfg.PublicURL + "/updates/" + filename,
		Notes:          strings.TrimSpace(r.FormValue("notes")),
	}
	if err := s.store.SetUpdatePolicy(r.Context(), policy); err != nil {
		s.log.Error("release policy write failed", "error", err)
		writeError(w, http.StatusInternalServerError, "APK stored but update policy could not be saved")
		return
	}
	if err := s.LoadUpdatePolicy(r.Context()); err != nil {
		s.log.Error("release policy reload failed", "error", err)
		writeError(w, http.StatusInternalServerError, "APK stored but update policy could not be loaded")
		return
	}

	s.log.Info("release published", "version", version, "bytes", written, "file", filename)
	writeJSON(w, http.StatusCreated, s.updatePolicy.get())
}

// handleReleaseDownload serves immutable, signed APKs. They carry no household secrets,
// so downloads do not need a TV session and continue working through Android's installer.
func (s *Server) handleReleaseDownload(w http.ResponseWriter, r *http.Request) {
	filename := r.PathValue("filename")
	if !releaseFilenamePattern.MatchString(filename) {
		http.NotFound(w, r)
		return
	}
	w.Header().Set("Content-Type", "application/vnd.android.package-archive")
	w.Header().Set("Cache-Control", "public, max-age=31536000, immutable")
	http.ServeFile(w, r, filepath.Join(s.cfg.ReleaseDir, filename))
}