package uploads_test

import (
	"context"
	"os"
	"testing"
	"time"

	"github.com/stretchr/testify/assert"
	"github.com/stretchr/testify/require"

	"git.d-ma.be/mathias/tapir/internal/domain"
	"git.d-ma.be/mathias/tapir/internal/uploads"
)

// The duration limit is a claim in the file's header. The worker measures what was
// really converted and refuses both a recording that is longer than the limit (the
// header lied low) and one that ends far earlier than the file claimed (it was truncated
// and would otherwise yield a partial transcript with no warning) -- adversarial review F2.

// sizedConverter writes a (sparse) 16 kHz mono PCM WAV of the given length, without
// actually allocating it: 32,000 bytes per second plus a 44-byte header.
type sizedConverter struct{ seconds float64 }

func (c sizedConverter) ToWAV(_ context.Context, _, dst string) error {
	f, err := os.Create(dst)
	if err != nil {
		return err
	}
	defer func() { _ = f.Close() }()
	return f.Truncate(44 + int64(c.seconds*32000))
}

func durationWorker(t *testing.T, r *wrig, wavSeconds float64, max time.Duration) *uploads.Worker {
	t.Helper()
	opts := []uploads.WorkerOption{}
	if max > 0 {
		opts = append(opts, uploads.WithMaxDuration(max))
	}
	return uploads.NewWorker(r.st, sizedConverter{seconds: wavSeconds}, r.tr, r.tmp, time.Minute, opts...)
}

func jobWith(r *wrig, t *testing.T, claimed time.Duration) uploads.Job {
	j := r.spool(t, "a")
	j.Duration = claimed
	return j
}

func TestWorkerDuration_AConvertedLengthOverTheLimitFailsTheJobBeforeAnyEngineSeesIt(t *testing.T) {
	r := newWRig(t, time.Minute)
	w := durationWorker(t, r, 100*60, 90*time.Minute)

	w.Process(context.Background(), jobWith(r, t, 10*time.Second))

	_, failed := r.st.snapshot()
	assert.Equal(t, domain.UploadErrTooLong, failed["a"], "a header that claimed 10 s must not let 100 minutes through")
	assert.Empty(t, r.tr.paths, "no engine may be sent audio that is over the limit")
	assert.Empty(t, r.leftovers(t), "the audio is still deleted")
}

func TestWorkerDuration_JustOverTheLimitWithinTheSlackStillTranscribes(t *testing.T) {
	r := newWRig(t, time.Minute)
	w := durationWorker(t, r, 90*60+20, 90*time.Minute)

	w.Process(context.Background(), jobWith(r, t, 90*time.Minute))

	completed, failed := r.st.snapshot()
	assert.Empty(t, failed)
	assert.Contains(t, completed, "a", "ffmpeg rounds: 20 s over a 90-minute limit is not a lie")
}

func audioStepNote(r *wrig) string {
	for _, st := range r.st.lastSteps() {
		if st.Key == "audio" {
			return st.Note
		}
	}
	return ""
}

func TestWorkerDuration_AFileThatEndsFarEarlierThanItClaimedIsStillTranscribedAndSaysSo(t *testing.T) {
	// A container header can over-estimate a complete file (VBR MP3 without a Xing header
	// claimed 79 minutes for 20 real ones). Refusing it was wrong; staying silent about a
	// truncated one is wrong too. So it is transcribed, and the audio step carries a note.
	r := newWRig(t, time.Minute)
	w := durationWorker(t, r, 20*60, 90*time.Minute)

	w.Process(context.Background(), jobWith(r, t, 79*time.Minute))

	completed, failed := r.st.snapshot()
	assert.Empty(t, failed, "a complete recording with a bad header estimate must not be refused")
	assert.Contains(t, completed, "a")
	note := audioStepNote(r)
	assert.Contains(t, note, "20 min", "what was really transcribed")
	assert.Contains(t, note, "1 h 19 min", "what the file claimed")
	assert.Contains(t, note, "cut off", "and what to do if that is not a surprise")
}

func TestWorkerDuration_TheShortfallNoteIsPinnedAtEightyPercentAndTwoMinutes(t *testing.T) {
	tests := []struct {
		name    string
		claimed time.Duration
		wav     float64
		noted   bool
	}{
		{"79 percent of an hour", 60 * time.Minute, 0.79 * 3600, true},
		{"81 percent of an hour", 60 * time.Minute, 0.81 * 3600, false},
		{"exactly two minutes short and under 80 percent", 6 * time.Minute, 4 * 60, false},
		{"two minutes and a second short and under 80 percent", 6 * time.Minute, 4*60 - 1, true},
		{"unknown claimed length", 0, 20 * 60, false},
	}
	for _, tt := range tests {
		t.Run(tt.name, func(t *testing.T) {
			r := newWRig(t, time.Minute)
			w := durationWorker(t, r, tt.wav, 90*time.Minute)

			w.Process(context.Background(), jobWith(r, t, tt.claimed))

			assert.Equal(t, tt.noted, audioStepNote(r) != "")
			completed, _ := r.st.snapshot()
			assert.Contains(t, completed, "a", "a note never stops the job")
		})
	}
}

func TestWorkerDuration_TheTooLongToleranceIsExactlyThirtySeconds(t *testing.T) {
	tests := []struct {
		name string
		wav  float64
		fail bool
	}{
		{"at the limit plus 30 s", 90*60 + 30, false},
		{"at the limit plus 31 s", 90*60 + 31, true},
	}
	for _, tt := range tests {
		t.Run(tt.name, func(t *testing.T) {
			r := newWRig(t, time.Minute)
			w := durationWorker(t, r, tt.wav, 90*time.Minute)

			w.Process(context.Background(), jobWith(r, t, 90*time.Minute))

			_, failed := r.st.snapshot()
			if tt.fail {
				assert.Equal(t, domain.UploadErrTooLong, failed["a"])
			} else {
				assert.Empty(t, failed)
			}
		})
	}
}

func TestWorkerDuration_AnEstimateThatIsMerelyALittleOffIsNotTruncation(t *testing.T) {
	tests := []struct {
		name    string
		claimed time.Duration
		wav     float64
	}{
		{"five percent short", 60 * time.Minute, 57 * 60},
		{"under two minutes short of a long file", 60 * time.Minute, 59 * 60},
		{"unknown claimed length", 0, 20 * 60},
	}
	for _, tt := range tests {
		t.Run(tt.name, func(t *testing.T) {
			r := newWRig(t, time.Minute)
			w := durationWorker(t, r, tt.wav, 90*time.Minute)

			w.Process(context.Background(), jobWith(r, t, tt.claimed))

			completed, failed := r.st.snapshot()
			assert.Empty(t, failed)
			assert.Contains(t, completed, "a")
		})
	}
}

func TestWorkerDuration_WithNoMaximumConfiguredNothingIsMeasured(t *testing.T) {
	r := newWRig(t, time.Minute)
	w := durationWorker(t, r, 100*60, 0)

	w.Process(context.Background(), jobWith(r, t, 0))

	completed, _ := r.st.snapshot()
	assert.Contains(t, completed, "a")
	require.NotNil(t, w)
}