package handlers

import (
	"errors"
	"net/http"

	"github.com/gin-gonic/gin"
	"github.com/google/uuid"
	"go.uber.org/zap"

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

// QueueSessionHandler handles collaborative queue session HTTP requests (v0.203 Lot D1)
type QueueSessionHandler struct {
	svc    *services.QueueSessionService
	logger *zap.Logger
}

// NewQueueSessionHandler creates a new QueueSessionHandler
func NewQueueSessionHandler(svc *services.QueueSessionService, logger *zap.Logger) *QueueSessionHandler {
	return &QueueSessionHandler{svc: svc, logger: logger}
}

// CreateSession creates a new shared queue session
func (h *QueueSessionHandler) CreateSession(c *gin.Context) {
	userID, ok := GetUserIDUUID(c)
	if !ok {
		return
	}
	session, err := h.svc.CreateSession(c.Request.Context(), userID)
	if err != nil {
		RespondWithAppError(c, apperrors.Wrap(apperrors.ErrCodeInternal, "Failed to create session", err))
		return
	}
	RespondSuccess(c, http.StatusCreated, gin.H{
		"session":     session,
		"share_token": session.ShareToken,
		"share_url":   "/queue?session=" + session.ShareToken,
	})
}

// GetSession returns a session's queue (auth optional for joining via link)
func (h *QueueSessionHandler) GetSession(c *gin.Context) {
	token := c.Param("token")
	if token == "" {
		RespondWithAppError(c, apperrors.NewValidationError("token is required"))
		return
	}
	session, items, err := h.svc.GetSessionByToken(c.Request.Context(), token)
	if err != nil {
		if errors.Is(err, services.ErrQueueSessionNotFound) {
			RespondWithAppError(c, apperrors.NewNotFoundError("session not found"))
			return
		}
		RespondWithAppError(c, apperrors.Wrap(apperrors.ErrCodeInternal, "Failed to get session", err))
		return
	}
	// Map items to response with tracks
	type itemResp struct {
		ID       string      `json:"id"`
		Position int         `json:"position"`
		AddedAt  string      `json:"added_at"`
		Track    interface{} `json:"track,omitempty"`
	}
	respItems := make([]itemResp, 0, len(items))
	for _, it := range items {
		r := itemResp{
			ID:       it.ID.String(),
			Position: it.Position,
			AddedAt:  it.AddedAt.Format("2006-01-02T15:04:05Z07:00"),
		}
		if it.Track.ID != uuid.Nil {
			r.Track = it.Track
		}
		respItems = append(respItems, r)
	}
	RespondSuccess(c, http.StatusOK, gin.H{
		"session": session,
		"items":   respItems,
	})
}

// DeleteSession deletes a session (creator only)
func (h *QueueSessionHandler) DeleteSession(c *gin.Context) {
	userID, ok := GetUserIDUUID(c)
	if !ok {
		return
	}
	token := c.Param("token")
	if token == "" {
		RespondWithAppError(c, apperrors.NewValidationError("token is required"))
		return
	}
	if err := h.svc.DeleteSession(c.Request.Context(), token, userID); err != nil {
		if errors.Is(err, services.ErrQueueSessionNotFound) {
			RespondWithAppError(c, apperrors.NewNotFoundError("session not found"))
			return
		}
		if errors.Is(err, services.ErrQueueSessionForbidden) {
			RespondWithAppError(c, apperrors.NewForbiddenError("only the creator can delete this session"))
			return
		}
		RespondWithAppError(c, apperrors.Wrap(apperrors.ErrCodeInternal, "Failed to delete session", err))
		return
	}
	RespondSuccess(c, http.StatusOK, gin.H{"message": "session deleted"})
}

// AddToSessionRequest represents the request body
type AddToSessionRequest struct {
	TrackID uuid.UUID `json:"track_id" binding:"required"`
}

// AddToSession adds a track to a session's queue
func (h *QueueSessionHandler) AddToSession(c *gin.Context) {
	token := c.Param("token")
	if token == "" {
		RespondWithAppError(c, apperrors.NewValidationError("token is required"))
		return
	}
	var req AddToSessionRequest
	if err := c.ShouldBindJSON(&req); err != nil {
		RespondWithAppError(c, apperrors.NewValidationError("track_id is required"))
		return
	}
	if err := h.svc.AddToSession(c.Request.Context(), token, req.TrackID); err != nil {
		if errors.Is(err, services.ErrQueueSessionNotFound) {
			RespondWithAppError(c, apperrors.NewNotFoundError("session not found"))
			return
		}
		RespondWithAppError(c, apperrors.Wrap(apperrors.ErrCodeInternal, "Failed to add to session", err))
		return
	}
	// Return updated session
	session, items, _ := h.svc.GetSessionByToken(c.Request.Context(), token)
	RespondSuccess(c, http.StatusCreated, gin.H{"session": session, "items": items})
}

// RemoveFromSession removes an item from a session's queue
func (h *QueueSessionHandler) RemoveFromSession(c *gin.Context) {
	token := c.Param("token")
	if token == "" {
		RespondWithAppError(c, apperrors.NewValidationError("token is required"))
		return
	}
	itemID, err := uuid.Parse(c.Param("id"))
	if err != nil {
		RespondWithAppError(c, apperrors.NewValidationError("invalid item ID"))
		return
	}
	if err := h.svc.RemoveFromSession(c.Request.Context(), token, itemID); err != nil {
		if errors.Is(err, services.ErrQueueSessionNotFound) {
			RespondWithAppError(c, apperrors.NewNotFoundError("session or item not found"))
			return
		}
		RespondWithAppError(c, apperrors.Wrap(apperrors.ErrCodeInternal, "Failed to remove from session", err))
		return
	}
	RespondSuccess(c, http.StatusOK, gin.H{"message": "item removed"})
}