package handlers

import (
	"errors"

	"Yimaru-Backend/internal/domain"
	"Yimaru-Backend/internal/repository"
	"Yimaru-Backend/internal/services/lessons"

	"github.com/gofiber/fiber/v2"
)

// RecordVideoEngagementHeartbeat godoc
// @Summary Report video playback progress
// @Description Records playback position for analytics (completion, replay, and drop-off). Send periodic heartbeats while watching; set ended=true when the viewer leaves. A new session starts after 30 minutes of inactivity or when ended=true on the prior session.
// @Tags videos
// @Accept json
// @Produce json
// @Param body body domain.VideoEngagementHeartbeatInput true "Playback heartbeat"
// @Success 200 {object} domain.Response{data=domain.VideoWatchSessionResponse}
// @Failure 400 {object} domain.ErrorResponse
// @Failure 403 {object} domain.ErrorResponse
// @Failure 404 {object} domain.ErrorResponse
// @Router /api/v1/videos/engagement/heartbeat [post]
func (h *Handler) RecordVideoEngagementHeartbeat(c *fiber.Ctx) error {
	var req domain.VideoEngagementHeartbeatInput
	if err := c.BodyParser(&req); err != nil {
		return c.Status(fiber.StatusBadRequest).JSON(domain.ErrorResponse{
			Message: "Invalid request body",
			Error:   err.Error(),
		})
	}
	if valErrs, ok := h.validator.Validate(c, req); !ok {
		return c.Status(fiber.StatusBadRequest).JSON(domain.ErrorResponse{
			Message: "Validation failed",
			Error:   firstValidationError(valErrs),
		})
	}

	uid := c.Locals("user_id").(int64)
	role := c.Locals("role").(domain.Role)

	if req.ContentKind == domain.VideoContentKindLMSLesson {
		les, err := h.lessonSvc.GetByID(c.Context(), req.ContentID)
		if err != nil {
			if errors.Is(err, lessons.ErrLessonNotFound) {
				return c.Status(fiber.StatusNotFound).JSON(domain.ErrorResponse{
					Message: "Lesson not found",
					Error:   err.Error(),
				})
			}
			return c.Status(fiber.StatusInternalServerError).JSON(domain.ErrorResponse{
				Message: "Failed to load lesson",
				Error:   err.Error(),
			})
		}
		if role.IsCustomerLearnerRole() && !les.VisibleToLearners() {
			return c.Status(fiber.StatusForbidden).JSON(domain.ErrorResponse{
				Message: "Only published lessons can be tracked",
				Error:   "LESSON_NOT_PUBLISHED",
			})
		}
		if role.UsesLMSSequentialGating() {
			ok, reason, err := h.lmsProgressSvc.CanAccessLesson(c.Context(), uid, req.ContentID)
			if err != nil {
				return c.Status(fiber.StatusInternalServerError).JSON(domain.ErrorResponse{
					Message: "Failed to verify lesson access",
					Error:   err.Error(),
				})
			}
			if !ok {
				return c.Status(fiber.StatusForbidden).JSON(domain.ErrorResponse{
					Message: reason,
					Error:   "LMS_PREREQUISITE_NOT_MET",
				})
			}
		}
	}

	res, err := h.videoEngagementSvc.RecordHeartbeat(c.Context(), uid, req)
	if err != nil {
		if errors.Is(err, repository.ErrVideoContentNotFound) {
			return c.Status(fiber.StatusNotFound).JSON(domain.ErrorResponse{
				Message: "Video content not found",
				Error:   err.Error(),
			})
		}
		if errors.Is(err, repository.ErrVideoContentHasNoURL) {
			return c.Status(fiber.StatusBadRequest).JSON(domain.ErrorResponse{
				Message: "Content has no video",
				Error:   err.Error(),
			})
		}
		return c.Status(fiber.StatusInternalServerError).JSON(domain.ErrorResponse{
			Message: "Failed to record video engagement",
			Error:   err.Error(),
		})
	}

	return c.JSON(domain.Response{
		Message:    "Video engagement recorded",
		Data:       res,
		Success:    true,
		StatusCode: fiber.StatusOK,
	})
}