// Fetch exchange rates from Frankfurter API (free, ECB rates)
// Usage: go run scripts/fetch_rates.go
package main

import (
	"database/sql"
	"encoding/json"
	"fmt"
	"log"
	"net/http"
	"time"

	_ "github.com/mattn/go-sqlite3"
)

const frankfurterAPI = "https://api.frankfurter.app/latest?from=USD"

type RatesResponse struct {
	Amount float64            `json:"amount"`
	Base   string             `json:"base"`
	Date   string             `json:"date"`
	Rates  map[string]float64 `json:"rates"`
}

func main() {
	db, err := sql.Open("sqlite3", "corporate.db")
	if err != nil {
		log.Fatal(err)
	}
	defer db.Close()

	fmt.Println("Fetching exchange rates from Frankfurter API (ECB rates)...")

	// Fetch rates from API
	resp, err := http.Get(frankfurterAPI)
	if err != nil {
		log.Fatalf("Failed to fetch rates: %v", err)
	}
	defer resp.Body.Close()

	var ratesData RatesResponse
	if err := json.NewDecoder(resp.Body).Decode(&ratesData); err != nil {
		log.Fatalf("Failed to decode response: %v", err)
	}

	fmt.Printf("Base: %s, Date: %s\n", ratesData.Base, ratesData.Date)
	fmt.Printf("Got rates for %d currencies\n", len(ratesData.Rates))

	// Update database
	now := time.Now().Unix()
	updated := 0
	notFound := []string{}

	for currency, rate := range ratesData.Rates {
		result, err := db.Exec(
			"UPDATE currencies SET exchange_rate = ?, rate_fetched_at = ? WHERE code = ?",
			rate, now, currency,
		)
		if err != nil {
			log.Printf("Error updating %s: %v", currency, err)
			continue
		}

		rows, _ := result.RowsAffected()
		if rows > 0 {
			updated++
		} else {
			notFound = append(notFound, currency)
		}
	}

	// Always set USD to 1.0
	db.Exec("UPDATE currencies SET exchange_rate = 1.0, rate_fetched_at = ? WHERE code = 'USD'", now)
	updated++

	fmt.Printf("\nUpdated %d currencies in database\n", updated)
	if len(notFound) > 0 {
		fmt.Printf("Rates not in our DB (consider adding): %v\n", notFound)
	}

	// Show sample rates
	fmt.Println("\n--- Sample Rates (1 USD = X units) ---")
	rows, _ := db.Query(`
		SELECT code, name, exchange_rate, decimals 
		FROM currencies 
		WHERE exchange_rate IS NOT NULL 
		ORDER BY code 
		LIMIT 15
	`)
	defer rows.Close()

	for rows.Next() {
		var code, name string
		var rate float64
		var decimals int
		rows.Scan(&code, &name, &rate, &decimals)
		fmt.Printf("  %s (%s): %.4f (%d decimals)\n", code, name, rate, decimals)
	}
}