package api

import (
	"context"
	"encoding/json"
	"errors"
	"io"
	"net/http"

	"jukebox_maker/internal/config"
	"jukebox_maker/internal/copier"
	"jukebox_maker/internal/disk"
)

func (s *Server) copyOptions(cfg *config.Config, diskInfo disk.DiskInfo, overwriteMode config.OverwriteMode) copier.Options {
	opts := copier.Options{
		DiskID:            diskInfo.DiskID,
		MountPath:         diskInfo.MountPath,
		MediaPath:         cfg.MediaPath,
		SourceRules:       cfg.Sources,
		AllowedExtensions: cfg.EffectiveAllowedExtensions(),
		OverwriteMode:     overwriteMode,
	}
	if p := diskInfo.Profile; p != nil {
		opts.DestFolder = p.DestFolder
		opts.ReserveFreeGB = p.ReserveFreeGB
		opts.FileSelectMode = config.FileSelectMode(p.FileSelectMode)
		opts.Transcode = p.Transcode
		opts.ShuffleDepth = p.ShuffleDepth
	} else {
		opts.DestFolder = cfg.DestFolder
		opts.ReserveFreeGB = cfg.ReserveFreeGB
		opts.FileSelectMode = cfg.FileSelectMode
	}
	return opts
}

func hasEnabledSources(cfg *config.Config) bool {
	for _, src := range cfg.Sources {
		if src.Enabled {
			return true
		}
	}
	return false
}

func decodeCopyMode(r *http.Request, fallback config.OverwriteMode) (config.OverwriteMode, error) {
	var req struct {
		Mode string `json:"mode"`
	}
	if r.Body != nil {
		if err := json.NewDecoder(r.Body).Decode(&req); err != nil && !errors.Is(err, io.EOF) {
			return "", err
		}
	}
	switch req.Mode {
	case "", "add":
		return config.OverwriteSkip, nil
	case "replace":
		return config.OverwriteDelete, nil
	default:
		return fallback, errors.New("invalid copy mode")
	}
}

func (s *Server) handleCopyStart(w http.ResponseWriter, r *http.Request) {
	diskID := r.PathValue("diskID")
	diskInfo, ok := s.deps.Watcher.DiskByID(diskID)
	if !ok || diskInfo.State != disk.DiskKnown {
		jsonErr(w, http.StatusUnprocessableEntity, "no initialized disk connected")
		return
	}

	cfg := s.deps.Config
	if !hasEnabledSources(cfg) {
		jsonErr(w, http.StatusUnprocessableEntity, "no source folders selected")
		return
	}

	overwriteMode, err := decodeCopyMode(r, cfg.OverwriteMode)
	if err != nil {
		if err.Error() == "invalid copy mode" {
			jsonErr(w, http.StatusBadRequest, err.Error())
			return
		}
		jsonErr(w, http.StatusBadRequest, "invalid JSON: "+err.Error())
		return
	}

	reserveGB := cfg.ReserveFreeGB
	if diskInfo.Profile != nil {
		reserveGB = diskInfo.Profile.ReserveFreeGB
	}
	if diskInfo.FreeBytes <= int64(reserveGB*1e9) {
		jsonErr(w, http.StatusUnprocessableEntity, "free space is below reserve threshold")
		return
	}

	opts := s.copyOptions(cfg, diskInfo, overwriteMode)

	taskID, err := s.deps.Copier.Start(context.Background(), opts)
	if err != nil {
		switch err.Error() {
		case "copy already running":
			jsonErr(w, http.StatusConflict, err.Error())
		default:
			jsonErr(w, http.StatusUnprocessableEntity, err.Error())
		}
		return
	}

	w.WriteHeader(http.StatusAccepted)
	jsonOK(w, map[string]string{"task_id": taskID})
}

func (s *Server) handleCopyStartSelected(w http.ResponseWriter, r *http.Request) {
	cfg := s.deps.Config
	if !hasEnabledSources(cfg) {
		jsonErr(w, http.StatusUnprocessableEntity, "no source folders selected")
		return
	}

	var req struct {
		MountPath string `json:"mount_path"`
		Mode      string `json:"mode"`
	}
	if err := json.NewDecoder(r.Body).Decode(&req); err != nil {
		jsonErr(w, http.StatusBadRequest, "invalid JSON: "+err.Error())
		return
	}
	diskInfo, err := s.deps.ProbeDisk(req.MountPath)
	if err != nil {
		jsonErr(w, http.StatusBadRequest, err.Error())
		return
	}
	if diskInfo.State != disk.DiskKnown {
		jsonErr(w, http.StatusUnprocessableEntity, "selected directory is not an initialized jukebox disk")
		return
	}

	overwriteMode := cfg.OverwriteMode
	switch req.Mode {
	case "", "add":
		overwriteMode = config.OverwriteSkip
	case "replace":
		overwriteMode = config.OverwriteDelete
	default:
		jsonErr(w, http.StatusBadRequest, "invalid copy mode")
		return
	}

	reserveGB := cfg.ReserveFreeGB
	if diskInfo.Profile != nil {
		reserveGB = diskInfo.Profile.ReserveFreeGB
	}
	if diskInfo.FreeBytes <= int64(reserveGB*1e9) {
		jsonErr(w, http.StatusUnprocessableEntity, "free space is below reserve threshold")
		return
	}

	if s.deps.OnDiskInit != nil {
		s.deps.OnDiskInit(diskInfo.MountPath, diskInfo.DiskID)
	}
	taskID, err := s.deps.Copier.Start(context.Background(), s.copyOptions(cfg, diskInfo, overwriteMode))
	if err != nil {
		switch err.Error() {
		case "copy already running":
			jsonErr(w, http.StatusConflict, err.Error())
		default:
			jsonErr(w, http.StatusUnprocessableEntity, err.Error())
		}
		return
	}

	w.WriteHeader(http.StatusAccepted)
	jsonOK(w, map[string]string{"task_id": taskID})
}

func (s *Server) handleCopyCancel(w http.ResponseWriter, r *http.Request) {
	diskID := r.PathValue("diskID")
	s.deps.Copier.Cancel(diskID)
	jsonOK(w, map[string]bool{"ok": true})
}

func (s *Server) handleTaskGet(w http.ResponseWriter, r *http.Request) {
	id := r.PathValue("id")
	t, ok := s.deps.Tasks.Get(id)
	if !ok {
		jsonErr(w, http.StatusNotFound, "task not found")
		return
	}
	jsonOK(w, t)
}