package main

import (
	"encoding/json"
	"fmt"
	"io"
	"net/http"
	"net/url"
)

const (
	APIKey  = "987b9c3428a3d0fe90179e3e6298d05e"
	BaseURL = "https://api.stlouisfed.org/fred"
)

func buildURL(endpoint string, params map[string]string) string {
	u, _ := url.Parse(BaseURL + endpoint)
	query := u.Query()
	query.Set("api_key", APIKey)
	query.Set("file_type", "json")
	for k, v := range params {
		if v != "" {
			query.Set(k, v)
		}
	}
	u.RawQuery = query.Encode()
	return u.String()
}

func fetchAndPrint(endpoint string, params map[string]string) {
	url := buildURL(endpoint, params)
	fmt.Printf("\n=== Testing %s ===\n", endpoint)
	fmt.Printf("URL: %s\n\n", url)

	resp, err := http.Get(url)
	if err != nil {
		fmt.Printf("Error: %v\n", err)
		return
	}
	defer resp.Body.Close()

	body, err := io.ReadAll(resp.Body)
	if err != nil {
		fmt.Printf("Error reading body: %v\n", err)
		return
	}

	var prettyJSON map[string]interface{}
	if err := json.Unmarshal(body, &prettyJSON); err == nil {
		output, _ := json.MarshalIndent(prettyJSON, "", "  ")
		fmt.Printf("Response:\n%s\n", output)
	} else {
		fmt.Printf("Response:\n%s\n", string(body))
	}
}

func main() {
	fmt.Println("========================================")
	fmt.Println("  FRED API 测试脚本")
	fmt.Println("========================================")

	fetchAndPrint("/series", map[string]string{"series_id": "GNPCA"})

	fetchAndPrint("/series/observations", map[string]string{
		"series_id":       "GNPCA",
		"limit":           "5",
		"observation_end": "2000-01-01",
	})

	fetchAndPrint("/series/search", map[string]string{
		"search_text": "GDP",
		"limit":       "3",
	})

	fetchAndPrint("/releases", map[string]string{
		"limit": "3",
	})

	fetchAndPrint("/releases/dates", map[string]string{
		"limit":      "3",
		"start_date": "2026-03-01",
		"end_date":   "2026-03-31",
	})

	fmt.Println("\n========================================")
	fmt.Println("  测试完成!")
	fmt.Println("========================================")
}