package api

import (
	"context"
	"encoding/json"
	"errors"
	"fmt"
	"net/http"
	"net/url"
	"regexp"
	"strconv"
	"strings"

	"github.com/Masterminds/squirrel"
	"github.com/navidrome/navidrome/log"
	"github.com/navidrome/navidrome/model"
	"github.com/navidrome/navidrome/server"
	. "github.com/navidrome/navidrome/utils/gg"
)

type contextKey string

const requestInContext contextKey = "request"

// storeRequestInContext is a middleware function that adds the full request object to the context.
func storeRequestInContext(next http.Handler) http.Handler {
	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		ctx := context.WithValue(r.Context(), requestInContext, r)
		next.ServeHTTP(w, r.WithContext(ctx))
	})
}

func toAPITrack(mf model.MediaFile) Track {
	return Track{
		Type: ResourceTypeTrack,
		Id:   mf.ID,
		Attributes: &TrackAttributes{
			Album:         mf.Album,
			Albumartist:   mf.AlbumArtist,
			Artist:        mf.Artist,
			Bitrate:       mf.BitRate,
			Bpm:           P(mf.Bpm),
			Channels:      mf.Channels,
			Comments:      P(mf.Comment),
			Disc:          P(mf.DiscNumber),
			Duration:      mf.Duration,
			Genre:         P(mf.Genre),
			Mimetype:      mf.ContentType(),
			RecordingMbid: P(mf.MbzTrackID),
			Size:          int(mf.Size),
			Title:         mf.Title,
			Track:         mf.TrackNumber,
			TrackMbid:     P(mf.MbzReleaseTrackID),
			Year:          P(mf.Year),
		},
		Relationships: &TrackRelationships{
			Albums:  &[]AlbumTrackRelationship{toAlbumRelationship(mf)},
			Artists: trackArtistRelationships(mf),
		},
	}
}

func trackArtistRelationships(mf model.MediaFile) []TrackArtistRelationship {
	var r []TrackArtistRelationship
	if mf.AlbumArtistID != "" {
		r = append(r, toArtistRelationship(mf.AlbumArtistID, ArtistRoleAlbumArtist))
	}
	if mf.ArtistID != "" {
		r = append(r, toArtistRelationship(mf.ArtistID, ArtistRoleArtist))
	}
	return r
}

func toArtistRelationship(id string, artist ArtistRole) TrackArtistRelationship {
	return TrackArtistRelationship{
		Data: ResourceObject{
			Type: ResourceTypeArtist,
			Id:   id,
		},
		Meta: ArtistMetaObject{Role: artist},
	}
}

func toAlbumRelationship(mf model.MediaFile) AlbumTrackRelationship {
	return AlbumTrackRelationship{
		Data: ResourceObject{
			Type: ResourceTypeAlbum,
			Id:   mf.AlbumID,
		},
	}
}

func toAPITracks(mfs model.MediaFiles) []Track {
	tracks := make([]Track, len(mfs))
	for i := range mfs {
		tracks[i] = toAPITrack(mfs[i])
	}
	return tracks
}

// toQueryOptions convert a params struct to a model.QueryOptions struct, to be used by the
// GetAll and CountAll functions. It assumes all GetXxxxParams functions have the exact same structure.
func toQueryOptions(ctx context.Context, params GetTracksParams) model.QueryOptions {
	var filters squirrel.And
	parseFilter := func(fs *[]string, op func(f, v string) squirrel.Sqlizer) {
		if fs != nil {
			for _, f := range *fs {
				parts := strings.SplitN(f, ":", 2)
				filters = append(filters, op(parts[0], parts[1]))
			}
		}
	}
	parseFilter(params.FilterEquals, func(f, v string) squirrel.Sqlizer { return squirrel.Eq{f: v} })
	parseFilter(params.FilterContains, func(f, v string) squirrel.Sqlizer { return squirrel.Like{f: "%" + v + "%"} })
	parseFilter(params.FilterStartsWith, func(f, v string) squirrel.Sqlizer { return squirrel.Like{f: v + "%"} })
	parseFilter(params.FilterEndsWith, func(f, v string) squirrel.Sqlizer { return squirrel.Like{f: "%" + v} })
	parseFilter(params.FilterGreaterThan, func(f, v string) squirrel.Sqlizer { return squirrel.Gt{f: v} })
	parseFilter(params.FilterGreaterOrEqual, func(f, v string) squirrel.Sqlizer { return squirrel.GtOrEq{f: v} })
	parseFilter(params.FilterLessThan, func(f, v string) squirrel.Sqlizer { return squirrel.Lt{f: v} })
	parseFilter(params.FilterLessOrEqual, func(f, v string) squirrel.Sqlizer { return squirrel.LtOrEq{f: v} })
	offset := V(params.PageOffset)
	limit := V(params.PageLimit)
	sort, err := toSortParams(params.Sort)
	if err != nil {
		log.Warn(ctx, "Ignoring invalid sort parameter", err)
	}
	return model.QueryOptions{Max: int(limit), Offset: int(offset), Filters: filters, Sort: sort}
}

var validSortPattern = regexp.MustCompile(`[a-zA-Z0-9_\-]`)

func toSortParams(sort *string) (string, error) {
	if sort == nil || *sort == "" {
		return "", nil
	}

	// Split input by comma
	inputCols := strings.Split(*sort, ",")

	var resultCols []string

	for _, col := range inputCols {
		trimmedCol := strings.TrimSpace(col)
		if trimmedCol == "" {
			continue
		}

		// Check for invalid prefix
		if !validSortPattern.Match([]byte(string(trimmedCol[0]))) {
			return "", errors.New("invalid sort parameter: " + trimmedCol)
		}

		colName := strings.TrimSpace(trimmedCol[1:])
		// Check for descending order
		if strings.HasPrefix(trimmedCol, "-") {
			resultCols = append(resultCols, fmt.Sprintf("%s desc", colName))
		} else {
			resultCols = append(resultCols, fmt.Sprintf("%s asc", trimmedCol))
		}
	}

	return strings.Join(resultCols, ","), nil
}

func apiErrorHandler(w http.ResponseWriter, _ *http.Request, err error) {
	var res ErrorObject
	switch {
	case errors.Is(err, model.ErrNotAuthorized):
		res = ErrorObject{Status: P(strconv.Itoa(http.StatusForbidden)), Title: P(http.StatusText(http.StatusForbidden))}
	case errors.Is(err, model.ErrNotFound):
		res = ErrorObject{Status: P(strconv.Itoa(http.StatusNotFound)), Title: P(http.StatusText(http.StatusNotFound))}
	default:
		res = ErrorObject{Status: P(strconv.Itoa(http.StatusInternalServerError)), Title: P(http.StatusText(http.StatusInternalServerError))}
	}
	w.Header().Set("Content-Type", "application/vnd.api+json")
	w.WriteHeader(403)

	_ = json.NewEncoder(w).Encode(ErrorList{[]ErrorObject{res}})
}

func validationErrorHandler(w http.ResponseWriter, message string, statusCode int) {
	_ = GetTracks400JSONResponse{BadRequestJSONResponse{Errors: []ErrorObject{
		{
			Status: P(strconv.Itoa(statusCode)),
			Title:  P(http.StatusText(statusCode)),
			Detail: P(message),
		},
	}}}.VisitGetTracksResponse(w)
}

func buildPaginationLinksAndMeta(totalItems int32, params GetTracksParams, resourceName string) (PaginationLinks, PaginationMeta) {
	pageLimit := *params.PageLimit
	pageOffset := *params.PageOffset

	totalPages := (totalItems + pageLimit - 1) / pageLimit
	currentPage := pageOffset/pageLimit + 1

	meta := PaginationMeta{
		CurrentPage: &currentPage,
		TotalItems:  &totalItems,
		TotalPages:  &totalPages,
	}

	var first, last, next, prev *string

	buildLink := func(page int32) *string {
		query := url.Values{}
		query.Add("page[offset]", strconv.Itoa(int(page*pageLimit)))
		query.Add("page[limit]", strconv.Itoa(int(pageLimit)))

		addFilterParams := func(paramName string, values *[]string) {
			if values == nil {
				return
			}
			for _, value := range *values {
				query.Add(paramName, value)
			}
		}

		addFilterParams("filter[equals]", params.FilterEquals)
		addFilterParams("filter[contains]", params.FilterContains)
		addFilterParams("filter[lessThan]", params.FilterLessThan)
		addFilterParams("filter[lessOrEqual]", params.FilterLessOrEqual)
		addFilterParams("filter[greaterThan]", params.FilterGreaterThan)
		addFilterParams("filter[greaterOrEqual]", params.FilterGreaterOrEqual)
		addFilterParams("filter[startsWith]", params.FilterStartsWith)
		addFilterParams("filter[endsWith]", params.FilterEndsWith)

		if params.Sort != nil {
			query.Add("sort", *params.Sort)
		}
		if params.Include != nil {
			query.Add("include", *params.Include)
		}

		link := resourceName
		if len(query) > 0 {
			link += "?" + query.Encode()
		}
		return &link
	}

	if totalPages > 0 {
		firstLink := buildLink(0)
		first = firstLink

		lastLink := buildLink(totalPages - 1)
		last = lastLink
	}

	if currentPage < totalPages {
		nextLink := buildLink(currentPage)
		next = nextLink
	}

	if currentPage > 1 {
		prevLink := buildLink(currentPage - 2)
		prev = prevLink
	}

	links := PaginationLinks{
		First: first,
		Last:  last,
		Next:  next,
		Prev:  prev,
	}

	return links, meta
}

func baseResourceUrl(ctx context.Context, resourceName string) string {
	r := ctx.Value(requestInContext).(*http.Request)
	baseUrl, _ := url.JoinPath(spec.Servers[0].URL, resourceName)
	return server.AbsoluteURL(r, baseUrl, nil)
}