package main

import (
	"bytes"
	"context"
	"database/sql"
	"encoding/json"
	"fmt"
	"io"
	"log"
	"net/http"
	"os"
	"time"

	_ "github.com/lib/pq"
)

func main() {
	supplyURL := os.Getenv("SUPPLY_URL")
	if supplyURL == "" {
		supplyURL = "http://127.0.0.1:8081"
	}
	consumer := os.Getenv("CONSUMER")
	if consumer == "" {
		consumer = "sub2api-bridge"
	}
	dbConn := os.Getenv("SUB2API_DB")
	if dbConn == "" {
		dbConn = "postgres://sub2api:***@localhost:5432/sub2api?sslmode=disable"
	}

	db, err := sql.Open("postgres", dbConn)
	if err != nil {
		log.Fatalf("open db: %v", err)
	}
	defer db.Close()
	if err := db.Ping(); err != nil {
		log.Fatalf("ping db: %v", err)
	}
	log.Println("connected to sub2api db")
	if err := ensureBridgeTable(db); err != nil {
		log.Fatalf("ensure table: %v", err)
	}

	cursor := ""
	for {
		ctx, cancel := context.WithTimeout(context.Background(), 30*time.Second)
		events, nextCursor, err := fetchPackageChanges(ctx, supplyURL, cursor)
		cancel()
		if err != nil {
			log.Printf("fetch error: %v", err)
			time.Sleep(10 * time.Second)
			continue
		}
		for _, evt := range events {
			if evt.GatewaySyncStatus != "pending" {
				log.Printf("skip non-pending event: %s status=%s", evt.EventID, evt.GatewaySyncStatus)
				continue
			}
			log.Printf("bridge event: %s package=%d model=%s", evt.EventID, evt.PackageID, evt.Model)
			if err := bridgeToSub2API(db, evt); err != nil {
				log.Printf("bridge error: %v", err)
				continue
			}
			ctx2, cancel2 := context.WithTimeout(context.Background(), 30*time.Second)
			ackErr := ackPackageChange(ctx2, supplyURL, evt.EventID, consumer, "applied", "synced to sub2api")
			cancel2()
			if ackErr != nil {
				log.Printf("ack error for %s: %v", evt.EventID, ackErr)
				continue
			}
			log.Printf("acked event: %s", evt.EventID)
		}
		if nextCursor == "" {
			log.Println("no more events, sleeping 10s")
			time.Sleep(10 * time.Second)
		} else {
			cursor = nextCursor
		}
	}
}

type PackageChangeEvent struct {
	EventID           string `json:"event_id"`
	AccountID         int64  `json:"account_id"`
	EventType         string `json:"event_type"`
	PackageID         int64  `json:"package_id"`
	Platform          string `json:"platform"`
	Model             string `json:"model"`
	OccurredAt        string `json:"occurred_at"`
	Version           int    `json:"version"`
	GatewaySyncStatus string `json:"gateway_sync_status"`
	RetryCount        int    `json:"retry_count"`
	NextRetryAt       string `json:"next_retry_at,omitempty"`
	LastFailureCategory string `json:"last_failure_category,omitempty"`
}

func fetchPackageChanges(ctx context.Context, baseURL, cursor string) ([]PackageChangeEvent, string, error) {
	url := fmt.Sprintf("%s/internal/supply-intelligence/gateway/package-changes", baseURL)
	if cursor != "" {
		url += "?cursor=" + cursor
	}
	req, err := http.NewRequestWithContext(ctx, http.MethodGet, url, nil)
	if err != nil {
		return nil, "", err
	}
	resp, err := http.DefaultClient.Do(req)
	if err != nil {
		return nil, "", err
	}
	defer resp.Body.Close()
	body, err := io.ReadAll(resp.Body)
	if err != nil {
		return nil, "", err
	}
	if resp.StatusCode != http.StatusOK {
		return nil, "", fmt.Errorf("HTTP %d: %s", resp.StatusCode, string(body))
	}
	var result struct {
		Items      []PackageChangeEvent `json:"items"`
		NextCursor string               `json:"next_cursor"`
	}
	if err := json.Unmarshal(body, &result); err != nil {
		return nil, "", err
	}
	return result.Items, result.NextCursor, nil
}

func ackPackageChange(ctx context.Context, baseURL, eventID, consumer, result, detail string) error {
	url := fmt.Sprintf("%s/internal/supply-intelligence/gateway/package-changes/%s/ack", baseURL, eventID)
	payload := map[string]string{
		"consumer": consumer,
		"result":   result,
		"detail":   detail,
	}
	body, _ := json.Marshal(payload)
	req, err := http.NewRequestWithContext(ctx, http.MethodPost, url, bytes.NewReader(body))
	if err != nil {
		return err
	}
	req.Header.Set("Content-Type", "application/json")
	resp, err := http.DefaultClient.Do(req)
	if err != nil {
		return err
	}
	defer resp.Body.Close()
	if resp.StatusCode != http.StatusNoContent {
		respBody, _ := io.ReadAll(resp.Body)
		return fmt.Errorf("HTTP %d: %s", resp.StatusCode, string(respBody))
	}
	return nil
}

func ensureBridgeTable(db *sql.DB) error {
	_, err := db.Exec(`CREATE TABLE IF NOT EXISTS supply_bridge_log (
		id SERIAL PRIMARY KEY,
		event_id TEXT NOT NULL UNIQUE,
		package_id BIGINT,
		platform TEXT,
		model TEXT,
		status TEXT,
		result TEXT,
		detail TEXT,
		created_at TIMESTAMPTZ DEFAULT NOW()
	)`)
	return err
}

func bridgeToSub2API(db *sql.DB, evt PackageChangeEvent) error {
	_, err := db.Exec(
		`INSERT INTO supply_bridge_log (event_id, package_id, platform, model, status, result, detail)
		VALUES ($1, $2, $3, $4, $5, $6, $7)
		ON CONFLICT (event_id) DO UPDATE SET
			status = EXCLUDED.status,
			result = EXCLUDED.result,
			detail = EXCLUDED.detail,
			created_at = NOW()`,
		evt.EventID, evt.PackageID, evt.Platform, evt.Model, evt.GatewaySyncStatus, "applied", "synced to sub2api",
	)
	return err
}