package executor

import (
	"context"
	"errors"
	"fmt"
	"testing"
	"time"
)

// --- isRateLimitError tests ---

func TestIsRateLimitError_RateLimitMessage(t *testing.T) {
	err := errors.New("claude exited with error: rate limit exceeded")
	if !isRateLimitError(err) {
		t.Error("want true for 'rate limit exceeded', got false")
	}
}

func TestIsRateLimitError_TooManyRequests(t *testing.T) {
	err := errors.New("too many requests to the API")
	if !isRateLimitError(err) {
		t.Error("want true for 'too many requests', got false")
	}
}

func TestIsRateLimitError_HTTP429(t *testing.T) {
	err := errors.New("API returned status 429")
	if !isRateLimitError(err) {
		t.Error("want true for '429', got false")
	}
}

func TestIsRateLimitError_Overloaded(t *testing.T) {
	err := errors.New("API overloaded, please retry later")
	if !isRateLimitError(err) {
		t.Error("want true for 'overloaded', got false")
	}
}

func TestIsRateLimitError_NonRateLimitError(t *testing.T) {
	err := errors.New("claude exited with error: exit status 1")
	if isRateLimitError(err) {
		t.Error("want false for non-rate-limit error, got true")
	}
}

func TestIsRateLimitError_NilError(t *testing.T) {
	if isRateLimitError(nil) {
		t.Error("want false for nil error, got true")
	}
}

// --- parseRetryAfter tests ---

func TestParseRetryAfter_RetryAfterSeconds(t *testing.T) {
	msg := "rate limit exceeded, retry after 30 seconds"
	d := parseRetryAfter(msg)
	if d != 30*time.Second {
		t.Errorf("want 30s, got %v", d)
	}
}

func TestParseRetryAfter_RetryAfterHeader(t *testing.T) {
	msg := "rate_limit_error: retry-after: 60"
	d := parseRetryAfter(msg)
	if d != 60*time.Second {
		t.Errorf("want 60s, got %v", d)
	}
}

func TestParseRetryAfter_NoRetryInfo(t *testing.T) {
	msg := "rate limit exceeded"
	d := parseRetryAfter(msg)
	if d != 0 {
		t.Errorf("want 0, got %v", d)
	}
}

// --- runWithBackoff tests ---

func TestRunWithBackoff_SuccessOnFirstTry(t *testing.T) {
	calls := 0
	fn := func() error {
		calls++
		return nil
	}
	err := runWithBackoff(context.Background(), 3, time.Millisecond, fn)
	if err != nil {
		t.Errorf("want nil error, got %v", err)
	}
	if calls != 1 {
		t.Errorf("want 1 call, got %d", calls)
	}
}

func TestRunWithBackoff_RetriesOnRateLimit(t *testing.T) {
	calls := 0
	fn := func() error {
		calls++
		if calls < 3 {
			return fmt.Errorf("rate limit exceeded")
		}
		return nil
	}
	err := runWithBackoff(context.Background(), 3, time.Millisecond, fn)
	if err != nil {
		t.Errorf("want nil error, got %v", err)
	}
	if calls != 3 {
		t.Errorf("want 3 calls, got %d", calls)
	}
}

func TestRunWithBackoff_GivesUpAfterMaxRetries(t *testing.T) {
	calls := 0
	rateLimitErr := fmt.Errorf("rate limit exceeded")
	fn := func() error {
		calls++
		return rateLimitErr
	}
	err := runWithBackoff(context.Background(), 3, time.Millisecond, fn)
	if err == nil {
		t.Fatal("want error after max retries, got nil")
	}
	// maxRetries=3: 1 initial call + 3 retries = 4 total calls
	if calls != 4 {
		t.Errorf("want 4 calls (1 initial + 3 retries), got %d", calls)
	}
}

func TestRunWithBackoff_DoesNotRetryNonRateLimitError(t *testing.T) {
	calls := 0
	fn := func() error {
		calls++
		return fmt.Errorf("permission denied")
	}
	err := runWithBackoff(context.Background(), 3, time.Millisecond, fn)
	if err == nil {
		t.Fatal("want error, got nil")
	}
	if calls != 1 {
		t.Errorf("want 1 call (no retry for non-rate-limit), got %d", calls)
	}
}

func TestRunWithBackoff_ContextCancellation(t *testing.T) {
	ctx, cancel := context.WithCancel(context.Background())
	calls := 0

	fn := func() error {
		calls++
		cancel() // cancel immediately after first call
		return fmt.Errorf("rate limit exceeded")
	}

	start := time.Now()
	err := runWithBackoff(ctx, 3, time.Second, fn) // large delay confirms ctx preempts wait
	elapsed := time.Since(start)

	if err == nil {
		t.Fatal("want error on context cancellation, got nil")
	}
	if elapsed > 500*time.Millisecond {
		t.Errorf("context cancellation too slow: %v (want < 500ms)", elapsed)
	}
	if calls != 1 {
		t.Errorf("want 1 call before cancellation, got %d", calls)
	}
}