//go:build llm_script

package main

import (
	"database/sql"
	"encoding/json"
	"fmt"
	"html"
	"io"
	"net/http"
	"os"
	"regexp"
	"sort"
	"strconv"
	"strings"
	"time"

	_ "github.com/lib/pq"
)

const subscriptionFetchMaxAttempts = 3

type subscriptionImportRecord struct {
	ProviderName    string
	ProviderNameCn  string
	ProviderCountry string
	ProviderWebsite string
	OperatorName    string
	OperatorNameCn  string
	OperatorCountry string
	OperatorWebsite string
	OperatorType    string
	PlanFamily      string
	PlanCode        string
	PlanName        string
	Tier            string
	BillingCycle    string
	Currency        string
	ListPrice       float64
	PriceUnit       string
	QuotaValue      int64
	QuotaUnit       string
	ContextWindow   int
	PlanScope       string
	ModelScope      []string
	SourceURL       string
	PublishedAt     string
	EffectiveDate   string
	Notes           string
	PublishedAtKnown bool
}

func loadSubscriptionImportEnv() {
	for _, path := range []string{".env.local", ".env"} {
		loadSubscriptionEnvFile(path)
	}
}

func loadSubscriptionEnvFile(path string) {
	data, err := os.ReadFile(path)
	if err != nil {
		return
	}

	for _, line := range strings.Split(string(data), "\n") {
		line = strings.TrimSpace(line)
		if line == "" || strings.HasPrefix(line, "#") {
			continue
		}
		key, value, ok := strings.Cut(line, "=")
		if !ok {
			continue
		}
		key = strings.TrimSpace(key)
		value = strings.Trim(strings.TrimSpace(value), `"'`)
		if key == "" {
			continue
		}
		if _, exists := os.LookupEnv(key); exists {
			continue
		}
		_ = os.Setenv(key, value)
	}
}

func subscriptionImportDB() (*sql.DB, error) {
	dsn := os.Getenv("DATABASE_URL")
	if dsn == "" {
		dsn = "postgres://long@/llm_intelligence?host=/var/run/postgresql"
	}
	return sql.Open("postgres", dsn)
}

func fetchSubscriptionPage(url string, fixture string, client *http.Client) (string, error) {
	if fixture != "" {
		data, err := os.ReadFile(fixture)
		if err != nil {
			return "", fmt.Errorf("read fixture %s: %w", fixture, err)
		}
		return string(data), nil
	}

	body, err := fetchSubscriptionPageWithRetry(url, client)
	if err == nil {
		return body, nil
	}
	if markdownURL, ok := markdownFallbackURL(url, err); ok {
		return fetchSubscriptionPageWithRetry(markdownURL, client)
	}
	return "", err
}

func fetchSubscriptionPageWithRetry(url string, client *http.Client) (string, error) {
	var lastErr error
	for attempt := 1; attempt <= subscriptionFetchMaxAttempts; attempt++ {
		body, retryable, err := fetchSubscriptionPageOnce(url, client)
		if err == nil {
			return body, nil
		}
		lastErr = err
		if !retryable || attempt == subscriptionFetchMaxAttempts {
			return "", err
		}
		time.Sleep(time.Duration(attempt) * 200 * time.Millisecond)
	}
	return "", lastErr
}


func fetchSubscriptionPageOnce(url string, client *http.Client) (string, bool, error) {
	req, err := http.NewRequest(http.MethodGet, url, nil)
	if err != nil {
		return "", false, err
	}
	req.Header.Set("User-Agent", "Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/136.0.0.0 Safari/537.36")
	req.Header.Set("Accept", "text/html,application/xhtml+xml,text/plain;q=0.9,*/*;q=0.8")
	req.Header.Set("Accept-Language", "zh-CN,zh;q=0.9,en;q=0.8")

	resp, err := client.Do(req)
	if err != nil {
		return "", isRetriableSubscriptionFetchError(err), fmt.Errorf("fetch %s: %w", url, err)
	}
	defer resp.Body.Close()

	if resp.StatusCode < 200 || resp.StatusCode >= 300 {
		retryable := resp.StatusCode == http.StatusForbidden ||
			resp.StatusCode == http.StatusTooManyRequests ||
			resp.StatusCode == http.StatusBadGateway ||
			resp.StatusCode == http.StatusServiceUnavailable ||
			resp.StatusCode == http.StatusGatewayTimeout
		return "", retryable, fmt.Errorf("fetch %s: unexpected status %d", url, resp.StatusCode)
	}
	body, err := io.ReadAll(resp.Body)
	if err != nil {
		return "", isRetriableSubscriptionFetchError(err), fmt.Errorf("read %s: %w", url, err)
	}
	return normalizeSubscriptionPage(string(body)), false, nil
}

func markdownFallbackURL(url string, err error) (string, bool) {
	if strings.TrimSpace(url) == "" || err == nil {
		return "", false
	}
	lower := strings.ToLower(err.Error())
	if !strings.Contains(lower, "status 403") && !strings.Contains(lower, "forbidden") {
		return "", false
	}
	if strings.HasSuffix(url, ".md") {
		return "", false
	}
	return strings.TrimRight(url, "/") + ".md", true
}

func isRetriableSubscriptionFetchError(err error) bool {
	if err == nil {
		return false
	}
	lower := strings.ToLower(err.Error())
	for _, marker := range []string{
		"eof",
		"timeout",
		"temporarily unavailable",
		"transport closed",
		"connection reset",
		"connection refused",
		"tls handshake timeout",
		"i/o timeout",
		"too many requests",
		"no such host",
		"forbidden",
		"status 403",
	} {
		if strings.Contains(lower, marker) {
			return true
		}
	}
	return false
}

func normalizeSubscriptionPage(raw string) string {
	text := raw
	scriptPattern := regexp.MustCompile(`(?is)<script[^>]*>.*?</script>`)
	stylePattern := regexp.MustCompile(`(?is)<style[^>]*>.*?</style>`)
	tagPattern := regexp.MustCompile(`(?is)<[^>]+>`)
	spacePattern := regexp.MustCompile(`[ \t]+`)

	text = scriptPattern.ReplaceAllString(text, "\n")
	text = stylePattern.ReplaceAllString(text, "\n")
	text = tagPattern.ReplaceAllString(text, "\n")
	text = html.UnescapeString(text)
	text = strings.ReplaceAll(text, "\r\n", "\n")
	text = strings.ReplaceAll(text, "\r", "\n")

	lines := strings.Split(text, "\n")
	cleaned := make([]string, 0, len(lines))
	for _, line := range lines {
		line = spacePattern.ReplaceAllString(line, " ")
		line = strings.TrimSpace(line)
		if line == "" {
			continue
		}
		cleaned = append(cleaned, line)
	}
	return strings.Join(cleaned, "\n")
}

func publishedAtFromText(raw string) (string, bool) {
	patterns := []*regexp.Regexp{
		regexp.MustCompile(`最近更新时间[:：]\s*(\d{4}-\d{2}-\d{2} \d{2}:\d{2}:\d{2})`),
		regexp.MustCompile(`更新时间[:：]?\s*(\d{4}-\d{2}-\d{2})`),
	}
	for _, pattern := range patterns {
		matches := pattern.FindStringSubmatch(raw)
		if len(matches) != 2 {
			continue
		}
		if len(matches[1]) == len("2006-01-02") {
			return matches[1] + " 00:00:00", true
		}
		return matches[1], true
	}
	return time.Now().Format("2006-01-02 15:04:05"), false
}

func effectiveDateFromPublishedAt(publishedAt string) string {
	if len(publishedAt) >= len("2006-01-02") {
		return publishedAt[:10]
	}
	return time.Now().Format("2006-01-02")
}

func upsertSubscriptionImportRecords(db *sql.DB, records []subscriptionImportRecord) error {
	type snapshotKey struct {
		providerID int64
		planCode   string
	}

	historyKeys := make(map[snapshotKey]struct{})
	for _, record := range records {
		providerID, err := ensureSubscriptionProvider(db, record)
		if err != nil {
			return err
		}
		operatorID, err := ensureSubscriptionOperator(db, record)
		if err != nil {
			return err
		}
		if !record.PublishedAtKnown {
			history, err := loadSubscriptionSnapshotHistory(db, providerID, record.PlanCode)
			if err != nil {
				return err
			}
			if _, err := reuseExistingSnapshotDates(&record, history); err != nil {
				return err
			}
		}

		publishedAt, err := time.Parse("2006-01-02 15:04:05", record.PublishedAt)
		if err != nil {
			return fmt.Errorf("parse published_at for %s: %w", record.PlanCode, err)
		}
		effectiveDate, err := time.Parse("2006-01-02", record.EffectiveDate)
		if err != nil {
			return fmt.Errorf("parse effective_date for %s: %w", record.PlanCode, err)
		}

		modelScopeRaw, err := json.Marshal(record.ModelScope)
		if err != nil {
			return fmt.Errorf("marshal model_scope for %s: %w", record.PlanCode, err)
		}

		_, err = db.Exec(
			`INSERT INTO subscription_plan (
				provider_id, operator_id, plan_family, plan_code, plan_name, tier,
				billing_cycle, currency, list_price, price_unit, quota_value, quota_unit,
				context_window, plan_scope, model_scope, source_url, published_at, effective_date, notes
			) VALUES (
				$1, $2, $3, $4, $5, $6,
				$7, $8, $9, $10, $11, $12,
				$13, $14, $15, $16, $17, $18, $19
			)
			ON CONFLICT (provider_id, plan_code, effective_date)
			DO UPDATE SET
				operator_id = EXCLUDED.operator_id,
				plan_family = EXCLUDED.plan_family,
				plan_name = EXCLUDED.plan_name,
				tier = EXCLUDED.tier,
				billing_cycle = EXCLUDED.billing_cycle,
				currency = EXCLUDED.currency,
				list_price = EXCLUDED.list_price,
				price_unit = EXCLUDED.price_unit,
				quota_value = EXCLUDED.quota_value,
				quota_unit = EXCLUDED.quota_unit,
				context_window = EXCLUDED.context_window,
				plan_scope = EXCLUDED.plan_scope,
				model_scope = EXCLUDED.model_scope,
				source_url = EXCLUDED.source_url,
				published_at = EXCLUDED.published_at,
				notes = EXCLUDED.notes,
				updated_at = CURRENT_TIMESTAMP`,
			providerID, operatorID, record.PlanFamily, record.PlanCode, record.PlanName, record.Tier,
			record.BillingCycle, record.Currency, record.ListPrice, record.PriceUnit, nullIfZeroInt64(record.QuotaValue), nullIfBlank(record.QuotaUnit),
			nullIfZeroIntCommon(record.ContextWindow), nullIfBlank(record.PlanScope), string(modelScopeRaw), record.SourceURL, publishedAt, effectiveDate, nullIfBlank(record.Notes),
		)
		if err != nil {
			return fmt.Errorf("upsert subscription_plan %s: %w", record.PlanCode, err)
		}
		historyKeys[snapshotKey{providerID: providerID, planCode: record.PlanCode}] = struct{}{}
	}
	for key := range historyKeys {
		if err := compactSubscriptionSnapshotHistory(db, key.providerID, key.planCode); err != nil {
			return err
		}
	}
	return nil
}

type subscriptionSnapshotRow struct {
	ID            int64
	PlanName      string
	Tier          string
	BillingCycle  string
	Currency      string
	ListPrice     float64
	PriceUnit     string
	QuotaValue    int64
	QuotaUnit     string
	ContextWindow int
	PlanScope     string
	ModelScope    string
	SourceURL     string
	Notes         string
	PublishedAt   time.Time
	EffectiveDate time.Time
}

func loadSubscriptionSnapshotHistory(db *sql.DB, providerID int64, planCode string) ([]subscriptionSnapshotRow, error) {
	rows, err := db.Query(
		`SELECT
			id,
			plan_name,
			tier,
			billing_cycle,
			currency,
			list_price,
			price_unit,
			COALESCE(quota_value, 0),
			COALESCE(quota_unit, ''),
			COALESCE(context_window, 0),
			COALESCE(plan_scope, ''),
			model_scope,
			source_url,
			COALESCE(notes, ''),
			published_at,
			effective_date
		FROM subscription_plan
		WHERE provider_id = $1 AND plan_code = $2
		ORDER BY effective_date DESC, published_at DESC NULLS LAST, id DESC`,
		providerID, planCode,
	)
	if err != nil {
		return nil, fmt.Errorf("load subscription snapshot history %s: %w", planCode, err)
	}
	defer rows.Close()

	history := make([]subscriptionSnapshotRow, 0)
	for rows.Next() {
		row := subscriptionSnapshotRow{}
		if err := rows.Scan(
			&row.ID,
			&row.PlanName,
			&row.Tier,
			&row.BillingCycle,
			&row.Currency,
			&row.ListPrice,
			&row.PriceUnit,
			&row.QuotaValue,
			&row.QuotaUnit,
			&row.ContextWindow,
			&row.PlanScope,
			&row.ModelScope,
			&row.SourceURL,
			&row.Notes,
			&row.PublishedAt,
			&row.EffectiveDate,
		); err != nil {
			return nil, fmt.Errorf("scan subscription snapshot history %s: %w", planCode, err)
		}
		history = append(history, row)
	}
	if err := rows.Err(); err != nil {
		return nil, fmt.Errorf("iterate subscription snapshot history %s: %w", planCode, err)
	}
	return history, nil
}

func reuseExistingSnapshotDates(record *subscriptionImportRecord, history []subscriptionSnapshotRow) (bool, error) {
	if record == nil || record.PublishedAtKnown || len(history) == 0 {
		return false, nil
	}

	modelScopeRaw, err := json.Marshal(record.ModelScope)
	if err != nil {
		return false, fmt.Errorf("marshal model_scope for snapshot comparison %s: %w", record.PlanCode, err)
	}

	for _, existing := range history {
		if existing.PlanName != record.PlanName ||
			existing.Tier != record.Tier ||
			existing.BillingCycle != record.BillingCycle ||
			existing.Currency != record.Currency ||
			existing.ListPrice != record.ListPrice ||
			existing.PriceUnit != record.PriceUnit ||
			existing.QuotaValue != record.QuotaValue ||
			existing.QuotaUnit != strings.TrimSpace(record.QuotaUnit) ||
			existing.ContextWindow != record.ContextWindow ||
			existing.PlanScope != strings.TrimSpace(record.PlanScope) ||
			existing.ModelScope != string(modelScopeRaw) ||
			existing.SourceURL != record.SourceURL ||
			existing.Notes != strings.TrimSpace(record.Notes) {
			continue
		}

		record.PublishedAt = existing.PublishedAt.Format("2006-01-02 15:04:05")
		record.EffectiveDate = existing.EffectiveDate.Format("2006-01-02")
		return true, nil
	}
	return false, nil
}

func compactSubscriptionSnapshotHistory(db *sql.DB, providerID int64, planCode string) error {
	history, err := loadSubscriptionSnapshotHistory(db, providerID, planCode)
	if err != nil {
		return err
	}
	for _, id := range redundantSnapshotRowIDs(history) {
		if _, err := db.Exec(`DELETE FROM subscription_plan WHERE id = $1`, id); err != nil {
			return fmt.Errorf("delete redundant subscription snapshot %d for %s: %w", id, planCode, err)
		}
	}
	return nil
}

func redundantSnapshotRowIDs(history []subscriptionSnapshotRow) []int64 {
	type signatureKey struct {
		PlanName      string
		Tier          string
		BillingCycle  string
		Currency      string
		ListPrice     float64
		PriceUnit     string
		QuotaValue    int64
		QuotaUnit     string
		ContextWindow int
		PlanScope     string
		ModelScope    string
		SourceURL     string
		Notes         string
	}
	type keptSnapshot struct {
		ID            int64
		EffectiveDate time.Time
		PublishedAt   time.Time
	}

	makeKey := func(row subscriptionSnapshotRow) signatureKey {
		return signatureKey{
			PlanName:      row.PlanName,
			Tier:          row.Tier,
			BillingCycle:  row.BillingCycle,
			Currency:      row.Currency,
			ListPrice:     row.ListPrice,
			PriceUnit:     row.PriceUnit,
			QuotaValue:    row.QuotaValue,
			QuotaUnit:     row.QuotaUnit,
			ContextWindow: row.ContextWindow,
			PlanScope:     row.PlanScope,
			ModelScope:    row.ModelScope,
			SourceURL:     row.SourceURL,
			Notes:         row.Notes,
		}
	}
	shouldReplace := func(current keptSnapshot, candidate subscriptionSnapshotRow) bool {
		if candidate.EffectiveDate.Before(current.EffectiveDate) {
			return true
		}
		if candidate.EffectiveDate.Equal(current.EffectiveDate) && candidate.PublishedAt.Before(current.PublishedAt) {
			return true
		}
		return candidate.EffectiveDate.Equal(current.EffectiveDate) && candidate.PublishedAt.Equal(current.PublishedAt) && candidate.ID < current.ID
	}

	keptBySignature := make(map[signatureKey]keptSnapshot)
	redundant := make([]int64, 0)
	for _, row := range history {
		key := makeKey(row)
		current, exists := keptBySignature[key]
		if !exists {
			keptBySignature[key] = keptSnapshot{ID: row.ID, EffectiveDate: row.EffectiveDate, PublishedAt: row.PublishedAt}
			continue
		}
		if shouldReplace(current, row) {
			redundant = append(redundant, current.ID)
			keptBySignature[key] = keptSnapshot{ID: row.ID, EffectiveDate: row.EffectiveDate, PublishedAt: row.PublishedAt}
			continue
		}
		redundant = append(redundant, row.ID)
	}
	sort.Slice(redundant, func(i, j int) bool { return redundant[i] < redundant[j] })
	return redundant
}

func ensureSubscriptionProvider(db *sql.DB, record subscriptionImportRecord) (int64, error) {
	var providerID int64
	err := db.QueryRow(`SELECT id FROM model_provider WHERE name = $1`, record.ProviderName).Scan(&providerID)
	if err == nil {
		return providerID, nil
	}
	if err != sql.ErrNoRows {
		return 0, err
	}

	err = db.QueryRow(
		`INSERT INTO model_provider (name, name_cn, country, website, status)
		 VALUES ($1, $2, $3, $4, 'active')
		 RETURNING id`,
		record.ProviderName, nullIfBlank(record.ProviderNameCn), record.ProviderCountry, nullIfBlank(record.ProviderWebsite),
	).Scan(&providerID)
	return providerID, err
}

func ensureSubscriptionOperator(db *sql.DB, record subscriptionImportRecord) (int64, error) {
	var operatorID int64
	err := db.QueryRow(`SELECT id FROM operator WHERE name = $1`, record.OperatorName).Scan(&operatorID)
	if err == nil {
		return operatorID, nil
	}
	if err != sql.ErrNoRows {
		return 0, err
	}

	err = db.QueryRow(
		`INSERT INTO operator (name, name_cn, country, website, description, status, type)
		 VALUES ($1, $2, $3, $4, $5, 'active', $6)
		 RETURNING id`,
		record.OperatorName, nullIfBlank(record.OperatorNameCn), record.OperatorCountry, nullIfBlank(record.OperatorWebsite),
		fmt.Sprintf("%s subscription import", record.OperatorName), record.OperatorType,
	).Scan(&operatorID)
	return operatorID, err
}

func summarizeSubscriptionImport(records []subscriptionImportRecord, getter func(subscriptionImportRecord) string) string {
	counts := make(map[string]int)
	keys := make([]string, 0)
	for _, record := range records {
		key := getter(record)
		if _, exists := counts[key]; !exists {
			keys = append(keys, key)
		}
		counts[key]++
	}
	sort.Strings(keys)

	parts := make([]string, 0, len(keys))
	for _, key := range keys {
		parts = append(parts, fmt.Sprintf("%s:%d", key, counts[key]))
	}
	return strings.Join(parts, ",")
}

func nullIfBlank(value string) any {
	if strings.TrimSpace(value) == "" {
		return nil
	}
	return value
}

func nullIfZeroInt64(value int64) any {
	if value == 0 {
		return nil
	}
	return value
}

func nullIfZeroIntCommon(value int) any {
	if value == 0 {
		return nil
	}
	return value
}

func mustParseSubscriptionPrice(raw string) float64 {
	cleaned := strings.ReplaceAll(raw, ",", "")
	cleaned = strings.ReplaceAll(cleaned, " ", "")
	value, _ := strconv.ParseFloat(cleaned, 64)
	return value
}

func mustParseSubscriptionInt64(raw string) int64 {
	cleaned := strings.ReplaceAll(raw, ",", "")
	cleaned = strings.ReplaceAll(cleaned, " ", "")
	value, _ := strconv.ParseInt(cleaned, 10, 64)
	return value
}

func firstNonEmptyText(values ...string) string {
	for _, value := range values {
		if strings.TrimSpace(value) != "" {
			return value
		}
	}
	return ""
}

func parseDecimalMultiplier(raw string, unit int64) int64 {
	cleaned := strings.TrimSpace(strings.ReplaceAll(raw, " ", ""))
	value, _ := strconv.ParseFloat(cleaned, 64)
	return int64(value * float64(unit))
}

func sliceSection(raw string, start string, end string) string {
	startIndex := strings.Index(raw, start)
	if startIndex < 0 {
		return ""
	}
	section := raw[startIndex+len(start):]
	if end != "" {
		if endIndex := strings.Index(section, end); endIndex >= 0 {
			section = section[:endIndex]
		}
	}
	return section
}