package feed

import (
	"net/http"
	"strconv"

	"github.com/gin-gonic/gin"

	apperrors "veza-backend-api/internal/errors"
	"veza-backend-api/internal/handlers"
)

// Handler handles the chronological tracks feed (v0.10.0 F210)
type Handler struct {
	service *Service
}

// NewHandler creates a new feed handler
func NewHandler(service *Service) *Handler {
	return &Handler{service: service}
}

// GetTracksFeed returns tracks from followed users, chronological, cursor-paginated.
// v0.10.1 F355: Adds by_genres section "Nouvelles sorties dans vos genres" when user follows genres.
// GET /api/v1/feed?cursor=...&limit=20&by_genres_cursor=...&by_genres_limit=10
// Requires authentication.
func (h *Handler) GetTracksFeed(c *gin.Context) {
	userID, ok := handlers.GetUserIDUUID(c)
	if !ok {
		return
	}

	limitStr := c.DefaultQuery("limit", "20")
	limit, err := strconv.Atoi(limitStr)
	if err != nil || limit < 1 || limit > 50 {
		handlers.RespondWithAppError(c, apperrors.NewValidationError("limit must be between 1 and 50"))
		return
	}

	cursor := c.Query("cursor")
	byGenresCursor := c.Query("by_genres_cursor")
	byGenresLimit := 10
	if l, err := strconv.Atoi(c.DefaultQuery("by_genres_limit", "10")); err == nil && l > 0 && l <= 50 {
		byGenresLimit = l
	}

	tracks, nextCursor, err := h.service.GetTracksFeed(c.Request.Context(), userID, limit, cursor)
	if err != nil {
		handlers.RespondWithAppError(c, apperrors.NewInternalErrorWrap("failed to get feed", err))
		return
	}

	resp := gin.H{"items": tracks}
	if nextCursor != "" {
		resp["next_cursor"] = nextCursor
	}

	// v0.10.1 F355: Section "Nouvelles sorties dans vos genres"
	if ds := h.service.GetDiscoverService(); ds != nil {
		byGenresTracks, byGenresNext, err := ds.GetTracksFromFollowedGenres(c.Request.Context(), userID, byGenresLimit, byGenresCursor)
		if err == nil {
			section := gin.H{"items": byGenresTracks}
			if byGenresNext != "" {
				section["next_cursor"] = byGenresNext
			}
			resp["by_genres"] = section
		}
	}

	handlers.RespondSuccess(c, http.StatusOK, resp)
}