package main

import (
	"context"
	"database/sql"
	"flag"
	"fmt"
	"log"
	"math"
	"os"
	"sort"
	"strings"
	"time"

	"weatherstation/internal/config"
	"weatherstation/internal/database"
)

var (
	providerOrder = []string{"open-meteo", "caiyun", "imdroid"}
	defaultWeight = []float64{0.4, 0.3, 0.3}
	timeLayout    = "2006-01-02 15:04:05"
)

func main() {
	var issuedInput string
	var issuedRange string
	var issuedStep int
	var stationFilter string
	var apply bool

	flag.StringVar(&issuedInput, "issued", "", "单个发布时间，例如 2025-10-05 20:00:00")
	flag.StringVar(&issuedRange, "issued_range", "", "发布时间范围，格式 \"开始,结束\"，例如 \"2025-10-05 20:00:00,2025-10-05 23:00:00\"")
	flag.IntVar(&issuedStep, "issued_step_hours", 1, "发布时间遍历步长（小时）")
	flag.StringVar(&stationFilter, "station", "", "可选，指定 station_id，仅处理该站点")
	flag.BoolVar(&apply, "apply", false, "直接写入 forecast_hourly（默认仅计算）")
	flag.Parse()

	if issuedInput == "" && issuedRange == "" {
		fmt.Fprintln(os.Stderr, "需要提供 --issued 或 --issued_range 参数")
		os.Exit(1)
	}
	if issuedInput != "" && issuedRange != "" {
		fmt.Fprintln(os.Stderr, "不能同时提供 --issued 与 --issued_range")
		os.Exit(1)
	}

	// 预先加载配置（也用于校验配置文件是否存在）
	_ = config.GetConfig()

	loc, err := time.LoadLocation("Asia/Shanghai")
	if err != nil {
		log.Printf("加载 Asia/Shanghai 时区失败，退回使用本地时区: %v", err)
		loc = time.Local
	}

	issuedTimes, err := buildIssuedTimes(loc, issuedInput, issuedRange, issuedStep)
	if err != nil {
		fmt.Fprintf(os.Stderr, "处理发布时间失败: %v\n", err)
		os.Exit(1)
	}
	if len(issuedTimes) == 0 {
		fmt.Fprintln(os.Stderr, "发布时间列表为空")
		return
	}

	ctx := context.Background()
	db := database.GetDB()
	defer database.Close()

	stations, err := loadStations(ctx, db, stationFilter)
	if err != nil {
		fmt.Fprintf(os.Stderr, "加载站点列表失败: %v\n", err)
		os.Exit(1)
	}

	if len(stations) == 0 {
		fmt.Println("没有找到匹配的站点或数据。")
		return
	}

	type summaryEntry struct {
		stationID string
		issuedAt  time.Time
		targets   [3]time.Time
		weighted  [3]float64
		hasSource bool
	}

	var sqlBuilder strings.Builder
	var summaries []summaryEntry

	sort.Strings(stations)
	for _, issuedAt := range issuedTimes {
		targetTimes := []time.Time{
			issuedAt.Add(1 * time.Hour),
			issuedAt.Add(2 * time.Hour),
			issuedAt.Add(3 * time.Hour),
		}
		for _, stationID := range stations {
			matrix, hasSource, err := loadProviderMatrix(ctx, db, stationID, issuedAt, targetTimes)
			if err != nil {
				fmt.Fprintf(os.Stderr, "站点 %s 读取数据失败: %v\n", stationID, err)
				continue
			}
			weighted := applyWeights(matrix, defaultWeight)

			if hasSource && len(targetTimes) == 3 {
				sqlBuilder.WriteString(renderSQL(stationID, issuedAt, targetTimes, weighted))
			}

			if apply && hasSource {
				if err := writeForecast(ctx, db, stationID, issuedAt, targetTimes, weighted); err != nil {
					fmt.Fprintf(os.Stderr, "写入站点 %s 失败: %v\n", stationID, err)
				}
			}

			var targetsArr [3]time.Time
			if len(targetTimes) == 3 {
				targetsArr = [3]time.Time{targetTimes[0], targetTimes[1], targetTimes[2]}
			}
			summaries = append(summaries, summaryEntry{
				stationID: stationID,
				issuedAt:  issuedAt,
				targets:   targetsArr,
				weighted:  weighted,
				hasSource: hasSource,
			})
		}
	}

	if sqlBuilder.Len() > 0 {
		label := buildIssuedLabel(issuedTimes)
		path, err := writeSQLFile(label, sqlBuilder.String())
		if err != nil {
			fmt.Fprintf(os.Stderr, "写入 SQL 文件失败: %v\n", err)
		} else {
			fmt.Printf("SQL 已保存至 %s\n", path)
		}
	}

	for _, item := range summaries {
		targetSlice := []time.Time{item.targets[0], item.targets[1], item.targets[2]}
		if err := printMixedSummaryFromDB(ctx, db, item.stationID, item.issuedAt, targetSlice, item.weighted, item.hasSource); err != nil {
			fmt.Fprintf(os.Stderr, "读取混合结果失败 station=%s issued=%s: %v\n", item.stationID, item.issuedAt.Format(timeLayout), err)
		}
	}
}

func buildIssuedTimes(loc *time.Location, single, rangeInput string, stepHours int) ([]time.Time, error) {
	if single == "" && rangeInput == "" {
		return nil, fmt.Errorf("未提供发布时间")
	}
	if single != "" {
		t, err := time.ParseInLocation(timeLayout, strings.TrimSpace(single), loc)
		if err != nil {
			return nil, fmt.Errorf("解析发布时间失败: %w", err)
		}
		return []time.Time{t}, nil
	}

	parts := strings.Split(rangeInput, ",")
	if len(parts) != 2 {
		return nil, fmt.Errorf("issued_range 格式应为 \"开始,结束\"")
	}

	start, err := time.ParseInLocation(timeLayout, strings.TrimSpace(parts[0]), loc)
	if err != nil {
		return nil, fmt.Errorf("解析开始时间失败: %w", err)
	}
	end, err := time.ParseInLocation(timeLayout, strings.TrimSpace(parts[1]), loc)
	if err != nil {
		return nil, fmt.Errorf("解析结束时间失败: %w", err)
	}
	if end.Before(start) {
		return nil, fmt.Errorf("结束时间早于开始时间")
	}
	if stepHours <= 0 {
		stepHours = 1
	}

	var list []time.Time
	for current := start; !current.After(end); current = current.Add(time.Duration(stepHours) * time.Hour) {
		list = append(list, current)
	}
	return list, nil
}

func buildIssuedLabel(times []time.Time) string {
	if len(times) == 0 {
		return "none"
	}
	if len(times) == 1 {
		return times[0].Format("20060102_150405")
	}
	first := times[0].Format("20060102_150405")
	last := times[len(times)-1].Format("20060102_150405")
	return fmt.Sprintf("%s-%s", first, last)
}

func loadStations(ctx context.Context, db *sql.DB, filter string) ([]string, error) {
	const baseQuery = `
SELECT station_id
FROM stations
WHERE latitude IS NOT NULL
  AND longitude IS NOT NULL`

	if filter != "" {
		row := db.QueryRowContext(ctx, baseQuery+" AND station_id = $1", filter)
		if err := row.Scan(&filter); err != nil {
			if err == sql.ErrNoRows {
				return nil, nil
			}
			return nil, err
		}
		return []string{filter}, nil
	}

	rows, err := db.QueryContext(ctx, baseQuery)
	if err != nil {
		return nil, err
	}
	defer rows.Close()

	var stations []string
	for rows.Next() {
		var id string
		if err := rows.Scan(&id); err != nil {
			return nil, err
		}
		stations = append(stations, id)
	}
	return stations, rows.Err()
}

func loadProviderMatrix(ctx context.Context, db *sql.DB, stationID string, issuedAt time.Time, targets []time.Time) (map[string][3]float64, bool, error) {
	result := make(map[string][3]float64, len(providerOrder))
	for _, p := range providerOrder {
		result[p] = [3]float64{}
	}

	issuedUpper := issuedAt.Add(1 * time.Minute)

	query := `
SELECT provider, forecast_time, COALESCE(rain_mm_x1000, 0)
FROM forecast_hourly
WHERE station_id = $1
  AND issued_at >= $2
  AND issued_at < $3
  AND provider IN ('open-meteo', 'caiyun', 'imdroid')
  AND forecast_time IN ($4, $5, $6)`

	rows, err := db.QueryContext(ctx, query, stationID, issuedAt, issuedUpper, targets[0], targets[1], targets[2])
	if err != nil {
		return nil, false, err
	}
	defer rows.Close()

	hasSource := false
	for rows.Next() {
		var provider string
		var ft time.Time
		var rain int64
		if err := rows.Scan(&provider, &ft, &rain); err != nil {
			return nil, false, err
		}

		offset := int(math.Round(ft.Sub(issuedAt).Hours()))
		if offset < 1 || offset > len(targets) {
			continue
		}

		hasSource = true
		data := result[provider]
		data[offset-1] = float64(rain) / 1000.0
		result[provider] = data
	}
	return result, hasSource, rows.Err()
}

func applyWeights(matrix map[string][3]float64, weight []float64) [3]float64 {
	var out [3]float64
	for hour := 0; hour < 3; hour++ {
		var sum float64
		for idx, provider := range providerOrder {
			sum += matrix[provider][hour] * weight[idx]
		}
		out[hour] = sum
	}
	return out
}

func renderSQL(stationID string, issuedAt time.Time, targets []time.Time, weighted [3]float64) string {
	const sqlTemplate = `
INSERT INTO forecast_hourly (
    station_id, provider, issued_at, forecast_time,
    rain_mm_x1000, temp_c_x100, humidity_pct, wind_speed_ms_x1000,
    wind_gust_ms_x1000, wind_dir_deg, precip_prob_pct, pressure_hpa_x100
) VALUES (
    '%s', 'imdroid_mix', '%s'::timestamptz, '%s'::timestamptz,
    %d, 0, 0, 0, 0, 0, 0, 0
)
ON CONFLICT (station_id, provider, issued_at, forecast_time)
DO UPDATE SET
    rain_mm_x1000 = EXCLUDED.rain_mm_x1000,
    temp_c_x100 = EXCLUDED.temp_c_x100,
    humidity_pct = EXCLUDED.humidity_pct,
    wind_speed_ms_x1000 = EXCLUDED.wind_speed_ms_x1000,
    wind_gust_ms_x1000 = EXCLUDED.wind_gust_ms_x1000,
    wind_dir_deg = EXCLUDED.wind_dir_deg,
    precip_prob_pct = EXCLUDED.precip_prob_pct,
    pressure_hpa_x100 = EXCLUDED.pressure_hpa_x100;
`
	var b strings.Builder
	fmt.Fprintf(&b, "-- SQL 输出 (默认未执行) station=%s\n", stationID)
	for idx, ft := range targets {
		rainInt := int64(math.Round(weighted[idx] * 1000))
		fmt.Fprintf(&b, sqlTemplate, stationID, issuedAt.Format(time.RFC3339), ft.Format(time.RFC3339), rainInt)
	}
	b.WriteByte('\n')
	return b.String()
}

func printMixedSummaryFromDB(ctx context.Context, db *sql.DB, stationID string, issuedAt time.Time, targets []time.Time, expected [3]float64, hasSource bool) error {
	query := `
SELECT forecast_time, COALESCE(rain_mm_x1000, 0)
FROM forecast_hourly
WHERE station_id = $1
  AND provider = 'imdroid_mix'
  AND issued_at = $2
  AND forecast_time IN ($3, $4, $5)
ORDER BY forecast_time`

	rows, err := db.QueryContext(ctx, query, stationID, issuedAt, targets[0], targets[1], targets[2])
	if err != nil {
		return err
	}
	defer rows.Close()

	type entry struct {
		ft   time.Time
		rain float64
	}
	var list []entry
	for rows.Next() {
		var ft time.Time
		var rain int64
		if err := rows.Scan(&ft, &rain); err != nil {
			return err
		}
		list = append(list, entry{ft: ft, rain: float64(rain) / 1000.0})
	}
	if err := rows.Err(); err != nil {
		return err
	}

	if len(list) == 0 {
		fmt.Printf("imdroid_mix station=%s issued=%s => [", stationID, issuedAt.Format(timeLayout))
		for idx, ft := range targets {
			if idx > 0 {
				fmt.Print(", ")
			}
			fmt.Printf("{hour:%d, dt:\"%s\", rain_mm:%.3f}", idx+1, ft.Format(timeLayout), expected[idx])
		}
		label := "computed"
		if !hasSource {
			label += ", no_source"
		}
		fmt.Printf("] (%s)\n", label)
		return nil
	}

	fmt.Printf("imdroid_mix station=%s issued=%s => [", stationID, issuedAt.Format(timeLayout))
	for idx, item := range list {
		if idx > 0 {
			fmt.Print(", ")
		}
		fmt.Printf("{hour:%d, dt:\"%s\", rain_mm:%.3f}", idx+1, item.ft.Format(timeLayout), item.rain)
	}
	fmt.Println("] (db)")
	return nil
}

func writeSQLFile(label string, sqlContent string) (string, error) {
	if !strings.HasSuffix(sqlContent, "\n") {
		sqlContent += "\n"
	}
	runKey := time.Now().Format("20060102_150405")
	filename := fmt.Sprintf("imdroid_mix_%s_%s.sql", label, runKey)
	if err := os.WriteFile(filename, []byte(sqlContent), 0o644); err != nil {
		return "", err
	}
	return filename, nil
}

func writeForecast(ctx context.Context, db *sql.DB, stationID string, issuedAt time.Time, targets []time.Time, weighted [3]float64) error {
	for idx, ft := range targets {
		rain := int64(math.Round(weighted[idx] * 1000))
		_, err := db.ExecContext(ctx, `
INSERT INTO forecast_hourly (
    station_id, provider, issued_at, forecast_time,
    rain_mm_x1000, temp_c_x100, humidity_pct, wind_speed_ms_x1000,
    wind_gust_ms_x1000, wind_dir_deg, precip_prob_pct, pressure_hpa_x100
) VALUES ($1, 'imdroid_mix', $2, $3, $4, 0, 0, 0, 0, 0, 0, 0)
ON CONFLICT (station_id, provider, issued_at, forecast_time)
DO UPDATE SET
    rain_mm_x1000 = EXCLUDED.rain_mm_x1000,
    temp_c_x100 = EXCLUDED.temp_c_x100,
    humidity_pct = EXCLUDED.humidity_pct,
    wind_speed_ms_x1000 = EXCLUDED.wind_speed_ms_x1000,
    wind_gust_ms_x1000 = EXCLUDED.wind_gust_ms_x1000,
    wind_dir_deg = EXCLUDED.wind_dir_deg,
    precip_prob_pct = EXCLUDED.precip_prob_pct,
    pressure_hpa_x100 = EXCLUDED.pressure_hpa_x100
`, stationID, issuedAt, ft, rain)
		if err != nil {
			return err
		}
	}
	return nil
}