package handlers

import (
	"bookhoard/internal/database"
	"bookhoard/internal/services"
	"errors"
	"net/http"

	"github.com/google/uuid"
	"github.com/jackc/pgx/v5/pgtype"
	"github.com/labstack/echo/v5"
)

// StatsHandler serves the reading-statistics API (/api/stats/*) backed
// by the StatisticsService. The server owns every conversion: clients
// receive user-timezone-rendered strings plus raw minute/page counts.
type StatsHandler struct {
	statsService *services.StatisticsService
}

func NewStatsHandler(statsService *services.StatisticsService) *StatsHandler {
	return &StatsHandler{statsService: statsService}
}

func mustUser(c *echo.Context) (database.Users, bool) {
	user, ok := c.Get("user").(database.Users)
	return user, ok
}

// Summary handles GET /api/stats/summary?range=7|30|90|year — the /stats
// page's complete payload: totals, daily arrays, streaks, most-active
// day, top books, per-library breakdown.
func (h *StatsHandler) Summary(c *echo.Context) error {
	user, ok := mustUser(c)
	if !ok {
		return echo.NewHTTPError(http.StatusUnauthorized, "invalid user")
	}
	summary, err := h.statsService.UserSummary(c.Request().Context(),
		pgtype.UUID{Bytes: user.ID.Bytes, Valid: true},
		user.Timezone.String,
		c.QueryParam("range"),
	)
	if err != nil {
		if err.Error()[:7] == "invalid" {
			return echo.NewHTTPError(http.StatusBadRequest, err.Error())
		}
		return echo.NewHTTPError(http.StatusInternalServerError, err.Error())
	}
	return c.JSON(http.StatusOK, summary)
}

// ThisWeek handles GET /api/stats/this-week — the dashboard widget's
// data: rolling 7-day totals vs the previous seven days, plus streak.
// An optional ?library_id scopes the week to one library (the
// dashboard's library switcher drives it).
func (h *StatsHandler) ThisWeek(c *echo.Context) error {
	user, ok := mustUser(c)
	if !ok {
		return echo.NewHTTPError(http.StatusUnauthorized, "invalid user")
	}
	var libraryID pgtype.UUID
	if raw := c.QueryParam("library_id"); raw != "" {
		parsed, err := uuid.Parse(raw)
		if err != nil {
			return echo.NewHTTPError(http.StatusBadRequest, "invalid library id")
		}
		libraryID = pgtype.UUID{Bytes: parsed, Valid: true}
	}
	week, err := h.statsService.ThisWeek(c.Request().Context(),
		pgtype.UUID{Bytes: user.ID.Bytes, Valid: true},
		user.Timezone.String,
		libraryID,
	)
	if err != nil {
		return echo.NewHTTPError(http.StatusInternalServerError, err.Error())
	}
	return c.JSON(http.StatusOK, week)
}

// LibraryUsage handles GET /api/stats/library-usage?library_id=<uuid|omit>
// — the /stats Library tab: media_items INVENTORY aggregates (items,
// authors, narrators, size, audio hours, pages, top genres/authors,
// longest/largest items) for one library or the All-libraries scope.
// Family lens: a library_id outside the requester's visible set is a 403,
// never a silent pass (AGENTS.md standing rule; history: 431fec0).
// Omitted library_id aggregates across all visible libraries. No time
// dimension — that is the reading tab's business.
func (h *StatsHandler) LibraryUsage(c *echo.Context) error {
	user, ok := mustUser(c)
	if !ok {
		return echo.NewHTTPError(http.StatusUnauthorized, "invalid user")
	}

	var libraryID pgtype.UUID
	if raw := c.QueryParam("library_id"); raw != "" {
		parsed, err := uuid.Parse(raw)
		if err != nil {
			return echo.NewHTTPError(http.StatusBadRequest, "invalid library id")
		}
		libraryID = pgtype.UUID{Bytes: parsed, Valid: true}
	}

	stats, err := h.statsService.LibraryUsage(c.Request().Context(),
		pgtype.UUID{Bytes: user.ID.Bytes, Valid: true},
		libraryID,
	)
	if err != nil {
		if errors.Is(err, services.ErrLibraryNotVisible) {
			return echo.NewHTTPError(http.StatusForbidden, "library not in the user's visible set")
		}
		return echo.NewHTTPError(http.StatusInternalServerError, err.Error())
	}
	return c.JSON(http.StatusOK, stats)
}

// BookStats handles GET /api/stats/books/:id — the per-book card on the
// book detail page (lifetime totals + recent sessions).
func (h *StatsHandler) BookStats(c *echo.Context) error {
	user, ok := mustUser(c)
	if !ok {
		return echo.NewHTTPError(http.StatusUnauthorized, "invalid user")
	}
	mediaItemID, err := uuid.Parse(c.Param("id"))
	if err != nil {
		return echo.NewHTTPError(http.StatusBadRequest, "invalid media item id")
	}
	stats, err := h.statsService.BookStats(c.Request().Context(),
		pgtype.UUID{Bytes: user.ID.Bytes, Valid: true},
		mediaItemID,
		user.Timezone.String,
	)
	if err != nil {
		return echo.NewHTTPError(http.StatusInternalServerError, err.Error())
	}
	return c.JSON(http.StatusOK, stats)
}