package cli

import (
	"context"
	"errors"
	"fmt"
	"io"
	"net/http"
	"strings"
	"time"

	"github.com/urfave/cli/v2"
)

// manifestFetchTimeout bounds HTTP requests made to fetch a manifest.
const manifestFetchTimeout = 30 * time.Second

// errHTTPStatus indicates an HTTP response with a non-OK status code.
//
// Its text is the literal "HTTP" prefix of the rendered "HTTP <code>"
// message that mfer has always printed, so that wrapping it does not
// change any user-visible output. Match it with errors.Is; do not read
// its message.
var errHTTPStatus = errors.New("HTTP")

// isHTTPURL returns true if the string starts with http:// or https://.
func isHTTPURL(s string) bool {
	return strings.HasPrefix(s, "http://") || strings.HasPrefix(s, "https://")
}

// openManifestReader opens a manifest from a path or URL and returns a ReadCloser.
// The caller must close the returned reader.
func (mfa *CLIApp) openManifestReader(pathOrURL string) (io.ReadCloser, error) {
	if isHTTPURL(pathOrURL) {
		client := &http.Client{Timeout: manifestFetchTimeout}

		req, err := http.NewRequestWithContext(
			context.Background(), http.MethodGet, pathOrURL, nil,
		)
		if err != nil {
			return nil, fmt.Errorf("failed to fetch %s: %w", pathOrURL, err)
		}

		resp, err := client.Do(req)
		if err != nil {
			return nil, fmt.Errorf("failed to fetch %s: %w", pathOrURL, err)
		}

		if resp.StatusCode != http.StatusOK {
			_ = resp.Body.Close()

			return nil, fmt.Errorf("failed to fetch %s: %w %d",
				pathOrURL, errHTTPStatus, resp.StatusCode)
		}

		return resp.Body, nil
	}

	f, err := mfa.Fs.Open(pathOrURL)
	if err != nil {
		return nil, err
	}

	return f, nil
}

// resolveManifestArg resolves the manifest path from CLI arguments.
// HTTP(S) URLs are returned as-is. Directories are searched for index.mf/.index.mf.
// If no argument is given, the current directory is searched.
func (mfa *CLIApp) resolveManifestArg(ctx *cli.Context) (string, error) {
	if ctx.Args().Len() > 0 {
		arg := ctx.Args().Get(0)
		if isHTTPURL(arg) {
			return arg, nil
		}

		info, statErr := mfa.Fs.Stat(arg)
		if statErr == nil && info.IsDir() {
			return findManifest(mfa.Fs, arg)
		}

		return arg, nil
	}

	return findManifest(mfa.Fs, ".")
}