package tasks

import (
	"encoding/binary"
	"math"
	"os"
	"os/exec"
	"strings"
	"testing"
)

func TestFloat32FromBytes(t *testing.T) {
	got := float32FromBytes([]byte{0x00, 0x00, 0x80, 0x3f}) // 1.0 little-endian
	if got != 1.0 {
		t.Fatalf("float32FromBytes() = %v, want 1.0", got)
	}
}

func TestMax(t *testing.T) {
	if got := max(1, 2); got != 2 {
		t.Fatalf("max() = %v, want 2", got)
	}
}

func TestExtractFrameNumber(t *testing.T) {
	if got := extractFrameNumber("render_0042.png"); got != 42 {
		t.Fatalf("extractFrameNumber() = %d, want 42", got)
	}
}

func TestCheckFFmpegSizeError(t *testing.T) {
	err := checkFFmpegSizeError("hardware does not support encoding at size ... constraints: width 128-4096 height 128-4096")
	if err == nil {
		t.Fatal("expected a size error")
	}
}

func TestDetectAlphaChannel_UsesExecSeam(t *testing.T) {
	orig := execCommand
	execCommand = fakeExecCommand
	defer func() { execCommand = orig }()

	if !detectAlphaChannel(&Context{}, "/tmp/frame.exr") {
		t.Fatal("expected alpha channel detection via mocked ffprobe output")
	}
}

func TestDetectHDR_UsesExecSeam(t *testing.T) {
	orig := execCommand
	execCommand = fakeExecCommand
	defer func() { execCommand = orig }()

	if !detectHDR(&Context{}, "/tmp/frame.exr") {
		t.Fatal("expected HDR detection via mocked ffmpeg sampling output")
	}
}

func fakeExecCommand(command string, args ...string) *exec.Cmd {
	cs := []string{"-test.run=TestExecHelperProcess", "--", command}
	cs = append(cs, args...)
	cmd := exec.Command(os.Args[0], cs...)
	cmd.Env = append(os.Environ(), "GO_WANT_HELPER_PROCESS=1")
	return cmd
}

func TestExecHelperProcess(t *testing.T) {
	if os.Getenv("GO_WANT_HELPER_PROCESS") != "1" {
		return
	}

	idx := 0
	for i, a := range os.Args {
		if a == "--" {
			idx = i
			break
		}
	}
	if idx == 0 || idx+1 >= len(os.Args) {
		os.Exit(2)
	}

	cmdName := os.Args[idx+1]
	cmdArgs := os.Args[idx+2:]

	switch cmdName {
	case "ffprobe":
		if containsArg(cmdArgs, "stream=pix_fmt:stream=codec_name") {
			_, _ = os.Stdout.WriteString("pix_fmt=gbrapf32le\ncodec_name=exr\n")
			os.Exit(0)
		}
		_, _ = os.Stdout.WriteString("gbrpf32le\n")
		os.Exit(0)
	case "ffmpeg":
		if containsArg(cmdArgs, "signalstats") {
			_, _ = os.Stderr.WriteString("signalstats failed")
			os.Exit(1)
		}
		if containsArg(cmdArgs, "rawvideo") {
			buf := make([]byte, 12)
			binary.LittleEndian.PutUint32(buf[0:4], math.Float32bits(1.5))
			binary.LittleEndian.PutUint32(buf[4:8], math.Float32bits(0.2))
			binary.LittleEndian.PutUint32(buf[8:12], math.Float32bits(0.1))
			_, _ = os.Stdout.Write(buf)
			os.Exit(0)
		}
		os.Exit(0)
	default:
		os.Exit(0)
	}
}

func containsArg(args []string, target string) bool {
	for _, a := range args {
		if strings.Contains(a, target) {
			return true
		}
	}
	return false
}