package main

import (
	"context"
	"errors"
	"fmt"
	"os"
	"os/exec"
	"path/filepath"
)

// tuiBinaryName is the compiled opentui configurator (see tui/ and `make tui`).
const tuiBinaryName = "rtsp-streamer-tui"

// findTUIBinary locates the opentui configurator. It is a sibling binary rather
// than something embedded in this one, because opentui is a TypeScript library
// compiled by Bun.
//
// Search order, most specific first:
//
//  1. $RTSP_STREAMER_TUI — an explicit path, for development
//  2. next to this executable — how `make install` lays it out
//  3. $PATH
func findTUIBinary() (string, error) {
	if p := os.Getenv("RTSP_STREAMER_TUI"); p != "" {
		if isExecutableFile(p) {
			return p, nil
		}
		return "", fmt.Errorf("RTSP_STREAMER_TUI=%s is not an executable file", p)
	}

	if exe, err := os.Executable(); err == nil {
		if resolved, err := filepath.EvalSymlinks(exe); err == nil {
			exe = resolved
		}
		if cand := filepath.Join(filepath.Dir(exe), tuiBinaryName); isExecutableFile(cand) {
			return cand, nil
		}
	}

	if p, err := exec.LookPath(tuiBinaryName); err == nil {
		return p, nil
	}

	return "", fmt.Errorf(
		"%s not found — build it with `make tui` (needs Bun) and install it with\n"+
			"`make install`, or point $RTSP_STREAMER_TUI at it.\n"+
			"To use the previous Bubble Tea configurator instead, run: rtsp-streamer tui --legacy",
		tuiBinaryName)
}

func isExecutableFile(path string) bool {
	st, err := os.Stat(path)
	return err == nil && !st.IsDir() && st.Mode()&0o111 != 0
}

// execTUI runs the configurator with this process's terminal, so it can take
// raw mode and the alternate screen directly. Its exit status becomes ours.
func execTUI(ctx context.Context, bin, cfg string) error {
	c := exec.CommandContext(ctx, bin, "--config", cfg)
	c.Stdin, c.Stdout, c.Stderr = os.Stdin, os.Stdout, os.Stderr
	// The TUI shells back to this binary for the bridge commands; tell it which
	// one, so a locally-built binary is not shadowed by an installed one.
	env := append(os.Environ(), "RTSP_STREAMER_CONFIG="+cfg)
	if self, err := os.Executable(); err == nil {
		env = append(env, "RTSP_STREAMER_BIN="+self)
	}
	c.Env = env

	err := c.Run()
	var exitErr *exec.ExitError
	if errors.As(err, &exitErr) {
		// The TUI already reported whatever went wrong on its own terminal.
		os.Exit(exitErr.ExitCode())
	}
	return err
}