package netreq

import (
	"bytes"
	"encoding/json"
	"fmt"
	"io"
	"net/http"
	"os"
	"path/filepath"
)

// Makes a GET request to the specified URL and returns the JSON response
// as a byte slice. If the request fails, it returns an error.
func GetJSON[T any](url string) ([]T, error) {
	fmt.Println("Fetching:", url)
	res, err := http.Get(url)
	if err != nil {
		return nil, err
	}
	defer res.Body.Close()

	body, err := io.ReadAll(res.Body)
	if err != nil {
		return nil, err
	}

	if res.StatusCode > 299 {
		return nil, fmt.Errorf("status %d: %s", res.StatusCode, string(body))
	}

	// 1. Trim whitespace to find the first actual JSON character
	trimmed := bytes.TrimSpace(body)
	if len(trimmed) == 0 {
		return nil, nil
	}

	var result []T

	// 2. Determine if we are looking at an Array [ ] or an Object { }
	if trimmed[0] == '[' {
		// It's already an array, unmarshal directly
		err = json.Unmarshal(body, &result)
	} else {
		// It's a single object, unmarshal into a single instance and wrap it
		var single T
		err = json.Unmarshal(body, &single)
		result = []T{single}
	}

	if err != nil {
		return nil, fmt.Errorf("failed to parse JSON: %w", err)
	}

	return result, nil
}

// Download downloads a specified object at a given url and places it in
// the provided dest directory.
func Download(name string, path string, url string) error {
	fullFilePath := filepath.Join(path, name)
	if err := os.MkdirAll(path, os.ModeDir); err != nil {
		return err
	}
	file, err := os.Create(fullFilePath)
	if err != nil {
		return err
	}
	defer file.Close()

	resp, err := http.Get(url)
	if err != nil {
		return err
	}
	defer resp.Body.Close()

	_, err = io.Copy(file, resp.Body)
	if err != nil {
		return err
	}

	return nil
}