package server

import (
	"net/http"
	"strconv"

	"music-server/internal/backend"
	"music-server/internal/logging"

	"github.com/labstack/echo/v5"
	"go.uber.org/zap"
)

const (
	defaultStatsLimit = 10
	maxStatsLimit     = 100
)

// StatisticsHandler handles statistics-related HTTP requests
type StatisticsHandler struct {
	stats *backend.StatisticsService
}

// NewStatisticsHandler creates a new StatisticsHandler
func NewStatisticsHandler(stats *backend.StatisticsService) *StatisticsHandler {
	return &StatisticsHandler{stats: stats}
}

// parseLimit reads the "limit" query parameter, defaulting to 10 and capping at 100.
func parseLimit(ctx *echo.Context) (int32, bool) {
	limitStr := ctx.QueryParam("limit")
	if limitStr == "" {
		return defaultStatsLimit, true
	}
	limit, err := strconv.Atoi(limitStr)
	if err != nil || limit <= 0 {
		return 0, false
	}
	return int32(min(limit, maxStatsLimit)), true
}

// withLimit runs a statistics query that takes a limit and writes the result as JSON.
func withLimit[T any](ctx *echo.Context, name string, query func(*echo.Context, int32) (T, error)) error {
	limit, ok := parseLimit(ctx)
	if !ok {
		return echo.NewHTTPError(http.StatusBadRequest, "Invalid limit parameter")
	}
	result, err := query(ctx, limit)
	return statsResult(ctx, name, result, err)
}

func statsResult[T any](ctx *echo.Context, name string, result T, err error) error {
	if err != nil {
		logging.GetLogger().Error("Failed to get statistics", zap.String("statistic", name), zap.Error(err))
		return echo.NewHTTPError(http.StatusInternalServerError, "Failed to get statistics")
	}
	return ctx.JSON(http.StatusOK, result)
}

// GetMostPlayedSoundtracks returns top N most played soundtracks with songs
//
//	@Summary		Get most played soundtracks
//	@Description	Returns the top N most played soundtracks with their songs
//	@Tags			statistics
//	@Produce		json
//	@Param			limit	query	int	false	"Number of results (default: 10, max: 100)"
//	@Success		200	{array}	backend.SoundtrackWithSongs
//	@Failure		400	{object}	map[string]string
//	@Failure		500	{object}	map[string]string
//	@Router			/api/v1/statistics/soundtracks/most-played [get]
func (h *StatisticsHandler) GetMostPlayedSoundtracks(ctx *echo.Context) error {
	return withLimit(ctx, "most played soundtracks", func(c *echo.Context, limit int32) ([]backend.SoundtrackWithSongs, error) {
		return h.stats.MostPlayedSoundtracks(c.Request().Context(), limit)
	})
}

// GetLeastPlayedSoundtracks returns top N least played soundtracks with songs
//
//	@Summary		Get least played soundtracks
//	@Description	Returns the top N least played soundtracks with their songs
//	@Tags			statistics
//	@Produce		json
//	@Param			limit	query	int	false	"Number of results (default: 10, max: 100)"
//	@Success		200	{array}	backend.SoundtrackWithSongs
//	@Failure		400	{object}	map[string]string
//	@Failure		500	{object}	map[string]string
//	@Router			/api/v1/statistics/soundtracks/least-played [get]
func (h *StatisticsHandler) GetLeastPlayedSoundtracks(ctx *echo.Context) error {
	return withLimit(ctx, "least played soundtracks", func(c *echo.Context, limit int32) ([]backend.SoundtrackWithSongs, error) {
		return h.stats.LeastPlayedSoundtracks(c.Request().Context(), limit)
	})
}

// GetMostPlayedSongs returns top N most played songs
//
//	@Summary		Get most played songs
//	@Description	Returns the top N most played songs with their soundtrack info
//	@Tags			statistics
//	@Produce		json
//	@Param			limit	query	int	false	"Number of results (default: 10, max: 100)"
//	@Success		200	{array}	backend.SongInfoForStats
//	@Failure		400	{object}	map[string]string
//	@Failure		500	{object}	map[string]string
//	@Router			/api/v1/statistics/songs/most-played [get]
func (h *StatisticsHandler) GetMostPlayedSongs(ctx *echo.Context) error {
	return withLimit(ctx, "most played songs", func(c *echo.Context, limit int32) ([]backend.SongInfoForStats, error) {
		return h.stats.MostPlayedSongs(c.Request().Context(), limit)
	})
}

// GetLeastPlayedSongs returns top N least played songs
//
//	@Summary		Get least played songs
//	@Description	Returns the top N least played songs with their soundtrack info
//	@Tags			statistics
//	@Produce		json
//	@Param			limit	query	int	false	"Number of results (default: 10, max: 100)"
//	@Success		200	{array}	backend.SongInfoForStats
//	@Failure		400	{object}	map[string]string
//	@Failure		500	{object}	map[string]string
//	@Router			/api/v1/statistics/songs/least-played [get]
func (h *StatisticsHandler) GetLeastPlayedSongs(ctx *echo.Context) error {
	return withLimit(ctx, "least played songs", func(c *echo.Context, limit int32) ([]backend.SongInfoForStats, error) {
		return h.stats.LeastPlayedSongs(c.Request().Context(), limit)
	})
}

// GetLastPlayedSoundtracks returns the most recently played soundtracks
//
//	@Summary		Get last played soundtracks
//	@Description	Returns the most recently played soundtracks with their songs
//	@Tags			statistics
//	@Produce		json
//	@Param			limit	query	int	false	"Number of results (default: 10, max: 100)"
//	@Success		200	{array}	backend.SoundtrackWithSongs
//	@Failure		400	{object}	map[string]string
//	@Failure		500	{object}	map[string]string
//	@Router			/api/v1/statistics/soundtracks/last-played [get]
func (h *StatisticsHandler) GetLastPlayedSoundtracks(ctx *echo.Context) error {
	return withLimit(ctx, "last played soundtracks", func(c *echo.Context, limit int32) ([]backend.SoundtrackWithSongs, error) {
		return h.stats.LastPlayedSoundtracks(c.Request().Context(), limit)
	})
}

// GetOldestPlayedSoundtracks returns the least recently played soundtracks
//
//	@Summary		Get oldest played soundtracks
//	@Description	Returns the least recently played soundtracks with their songs
//	@Tags			statistics
//	@Produce		json
//	@Param			limit	query	int	false	"Number of results (default: 10, max: 100)"
//	@Success		200	{array}	backend.SoundtrackWithSongs
//	@Failure		400	{object}	map[string]string
//	@Failure		500	{object}	map[string]string
//	@Router			/api/v1/statistics/soundtracks/oldest-played [get]
func (h *StatisticsHandler) GetOldestPlayedSoundtracks(ctx *echo.Context) error {
	return withLimit(ctx, "oldest played soundtracks", func(c *echo.Context, limit int32) ([]backend.SoundtrackWithSongs, error) {
		return h.stats.OldestPlayedSoundtracks(c.Request().Context(), limit)
	})
}

// GetNeverPlayedSoundtracks returns soundtracks that have never been played
//
//	@Summary		Get never played soundtracks
//	@Description	Returns all soundtracks that have never been played
//	@Tags			statistics
//	@Produce		json
//	@Success		200	{array}	backend.SoundtrackWithSongs
//	@Failure		500	{object}	map[string]string
//	@Router			/api/v1/statistics/soundtracks/never-played [get]
func (h *StatisticsHandler) GetNeverPlayedSoundtracks(ctx *echo.Context) error {
	result, err := h.stats.NeverPlayedSoundtracks(ctx.Request().Context())
	return statsResult(ctx, "never played soundtracks", result, err)
}

// GetStatisticsSummary returns overall statistics
//
//	@Summary		Get statistics summary
//	@Description	Returns overall play statistics
//	@Tags			statistics
//	@Produce		json
//	@Success		200	{object}	backend.StatisticsSummary
//	@Failure		500	{object}	map[string]string
//	@Router			/api/v1/statistics/summary [get]
func (h *StatisticsHandler) GetStatisticsSummary(ctx *echo.Context) error {
	result, err := h.stats.Summary(ctx.Request().Context())
	return statsResult(ctx, "summary", result, err)
}