package opencode

import (
	"context"
	"os"
	"path/filepath"
	"testing"
	"time"
)

// fakeOpenCode создаёт shell-скрипт, имитирующий opencode run:
//   $FAKE_MODE=ok  -> мгновенный успех, печатает NDJSON c session_id
//   $FAKE_MODE=slow-> спит долго (для idle/hard timeout)
//   $FAKE_MODE=fail-> exit 7 (resume-fallback)
func fakeOpenCode(t *testing.T, workdir string) string {
	t.Helper()
	bin := filepath.Join(workdir, "opencode")
	script := `#!/bin/sh
mode="${FAKE_MODE:-ok}"
case "$mode" in
  ok)
    echo '{"type":"text","part":{"text":"done"}}'
    echo '{"session_id":"sess-123"}'
    exit 0
    ;;
  slow)
    sleep 30
    ;;
  fail)
    echo '{"type":"text","part":{"text":"boom"}}'
    exit 7
    ;;
esac
`
	if err := os.WriteFile(bin, []byte(script), 0o755); err != nil {
		t.Fatalf("write fake opencode: %v", err)
	}
	return bin
}

func TestRun_Success(t *testing.T) {
	dir := t.TempDir()
	bin := fakeOpenCode(t, dir)
	t.Setenv("FAKE_MODE", "ok")

	r := &Runner{Bin: bin, PollInterval: 20 * time.Millisecond}
	res, err := r.Run(context.Background(), "task", dir, "dev", "")
	if err != nil {
		t.Fatalf("Run err: %v", err)
	}
	if res.RC != 0 {
		t.Errorf("RC = %d, want 0", res.RC)
	}
	if res.SessionID != "sess-123" {
		t.Errorf("SessionID = %q, want sess-123", res.SessionID)
	}
	if !contains(res.Stdout, "done") {
		t.Errorf("Stdout = %q, want to contain done", res.Stdout)
	}
}

func TestRun_IdleTimeout(t *testing.T) {
	dir := t.TempDir()
	bin := fakeOpenCode(t, dir)
	t.Setenv("FAKE_MODE", "slow")

	r := &Runner{Bin: bin, IdleTimeout: 50 * time.Millisecond,
		PollInterval: 10 * time.Millisecond}
	res, err := r.Run(context.Background(), "task", dir, "dev", "")
	if err != nil {
		t.Fatalf("Run err: %v", err)
	}
	if res.RC != -1 {
		t.Errorf("RC = %d, want -1 (timeout kill)", res.RC)
	}
}

func TestRun_ContextCancel(t *testing.T) {
	dir := t.TempDir()
	bin := fakeOpenCode(t, dir)
	t.Setenv("FAKE_MODE", "slow")

	ctx, cancel := context.WithCancel(context.Background())
	r := &Runner{Bin: bin, HardTimeout: time.Minute,
		PollInterval: 10 * time.Millisecond}
	done := make(chan *Result, 1)
	errCh := make(chan error, 1)
	go func() {
		res, err := r.Run(ctx, "task", dir, "dev", "")
		done <- res
		errCh <- err
	}()
	time.Sleep(30 * time.Millisecond)
	cancel()
	res := <-done
	if err := <-errCh; err != nil {
		t.Fatalf("Run err: %v", err)
	}
	if res.RC != -1 {
		t.Errorf("RC = %d, want -1", res.RC)
	}
}

func TestResumeDev_Fallback(t *testing.T) {
	dir := t.TempDir()
	bin := fakeOpenCode(t, dir)
	t.Setenv("FAKE_MODE", "fail")

	r := &Runner{Bin: bin, PollInterval: 20 * time.Millisecond}
	res, timedOut := r.ResumeDev(context.Background(), "task", dir, "lost-session")
	if timedOut {
		t.Error("timedOut = true, want false")
	}
	// fake fail всегда exit 7, fallback тоже 7 — проверяем что RC от fallback-вызова
	if res.RC != 7 {
		t.Errorf("RC = %d, want 7 (fallback повтор с тем же кодом)", res.RC)
	}
}

func contains(s, sub string) bool {
	return len(s) >= len(sub) && (s == sub || len(s) > 0 && indexOf(s, sub) >= 0)
}

func indexOf(s, sub string) int {
	for i := 0; i+len(sub) <= len(s); i++ {
		if s[i:i+len(sub)] == sub {
			return i
		}
	}
	return -1
}