package library

import (
	"bytes"
	"context"
	"errors"
	"fmt"
	"os/exec"
	"slices"
	"strings"
	"testing"
)

func TestParseFpcalcRaw(t *testing.T) {
	cases := []struct {
		name    string
		out     string
		want    []int32
		wantErr string
	}{
		{
			name: "signed output with negatives",
			out:  "DURATION=213\nFINGERPRINT=-1453821711,17,0,2147483647,-2147483648\n",
			want: []int32{-1453821711, 17, 0, 2147483647, -2147483648},
		},
		{
			name: "fingerprint line need not come second",
			out:  "FINGERPRINT=5,6\nDURATION=1\n",
			want: []int32{5, 6},
		},
		{
			// fpcalc's default is uint32. This value only appears when -signed
			// is missing, and storing it would need a reinterpretation nothing
			// performs.
			name:    "unsigned output is refused",
			out:     "DURATION=213\nFINGERPRINT=2841145585,17\n",
			wantErr: "item 0",
		},
		{name: "empty fingerprint", out: "DURATION=0\nFINGERPRINT=\n", wantErr: "empty fingerprint"},
		{name: "no fingerprint line", out: "DURATION=213\n", wantErr: "no FINGERPRINT= line"},
		{name: "non-numeric item", out: "FINGERPRINT=1,x,3\n", wantErr: "item 1"},
		{name: "trailing comma", out: "FINGERPRINT=1,2,\n", wantErr: "item 2"},
	}
	for _, tc := range cases {
		t.Run(tc.name, func(t *testing.T) {
			got, err := parseFpcalcRaw([]byte(tc.out))
			if tc.wantErr != "" {
				if err == nil || !strings.Contains(err.Error(), tc.wantErr) {
					t.Fatalf("err = %v, want one containing %q", err, tc.wantErr)
				}
				return
			}
			if err != nil {
				t.Fatalf("unexpected err: %v", err)
			}
			if !slices.Equal(got, tc.want) {
				t.Fatalf("got %v, want %v", got, tc.want)
			}
		})
	}
}

func TestParseStreamHash(t *testing.T) {
	// The real value ffmpeg printed for both files of the #3885 pair.
	const www = "24e2daa3b4a534ff1a8d1a76f67810205869daf89f728d83a16625da4d28a18e"

	got, err := parseStreamHash([]byte("SHA256=" + www + "\n"))
	if err != nil {
		t.Fatalf("unexpected err: %v", err)
	}
	if len(got) != 32 || got[0] != 0x24 || got[31] != 0x8e {
		t.Fatalf("decoded %x, want %s", got, www)
	}

	for name, out := range map[string]string{
		"no hash line":  "",
		"other hash":    "MD5=" + www[:32] + "\n",
		"not hex":       "SHA256=" + strings.Repeat("zz", 32) + "\n",
		"short digest":  "SHA256=" + www[:62] + "\n",
		"odd hex chars": "SHA256=" + www[:63] + "\n",
	} {
		if _, err := parseStreamHash([]byte(out)); err == nil {
			t.Errorf("%s: parsed %q without error", name, out)
		}
	}
}

// followedBy reports whether flag appears in args immediately followed by value.
func followedBy(args []string, flag, value string) bool {
	for i := 0; i+1 < len(args); i++ {
		if args[i] == flag && args[i+1] == value {
			return true
		}
	}
	return false
}

// The exact tier's stored hashes must stay comparable across ffmpeg upgrades,
// which only holds while the packets are copied rather than decoded. A decoded
// hash still matches within one ffmpeg build, so nothing else would notice the
// change until an image upgrade silently broke every stored value.
func TestStreamHashArgs_HashPacketsNotSamples(t *testing.T) {
	args := streamHashArgs("/music/a.mp3")
	for _, pair := range [][2]string{
		{"-c:a", "copy"}, // no decode
		{"-map", "0:a"},  // audio only: cover art stays out of the hash
		{"-f", "hash"},   // the hash muxer, not a file
		{"-hash", "sha256"},
		{"-i", "/music/a.mp3"},
	} {
		if !followedBy(args, pair[0], pair[1]) {
			t.Errorf("streamHashArgs lacks %s %s: %v", pair[0], pair[1], args)
		}
	}
}

func TestFpcalcArgs_RequestSignedRawOutput(t *testing.T) {
	args := fpcalcArgs("/music/a.flac", 90)
	for _, flag := range []string{"-raw", "-signed"} {
		if !slices.Contains(args, flag) {
			t.Errorf("fpcalcArgs lacks %s: %v", flag, args)
		}
	}
	if !followedBy(args, "-length", "90") {
		t.Errorf("fpcalcArgs does not pass the requested length: %v", args)
	}
	// fpcalc takes the file as its trailing positional argument.
	if args[len(args)-1] != "/music/a.flac" {
		t.Errorf("path is not last: %v", args)
	}
}

func TestStderrTail_KeepsTheCauseNotTheBanner(t *testing.T) {
	banner := bytes.Repeat([]byte("warning: skipping frame\n"), fpcalcStderrTail)
	got := stderrTail(append(banner, []byte("ERROR: could not decode\n")...))
	if len(got) != fpcalcStderrTail {
		t.Fatalf("tail is %d bytes, want the %d-byte cap", len(got), fpcalcStderrTail)
	}
	if !bytes.HasSuffix(got, []byte("ERROR: could not decode")) {
		t.Fatalf("tail dropped the final line: ...%q", got[len(got)-40:])
	}

	if got := stderrTail([]byte("  short  \n")); string(got) != "short" {
		t.Fatalf("short stderr = %q, want it trimmed and whole", got)
	}
}

// A stored failure is permanent until the file changes, so the classification
// decides whether a track is ever retried. Every inconclusive case here would,
// if misfiled as a verdict, silently exclude that track from duplicate
// detection for good.
func TestIsInconclusive(t *testing.T) {
	notInstalled := fmt.Errorf("fpcalc: %w", &exec.Error{Name: "fpcalc", Err: exec.ErrNotFound})
	cases := []struct {
		name string
		err  error
		want bool
	}{
		{"timeout", fmt.Errorf("fpcalc: no result: %w", errFingerprintTimeout), true},
		{"scan cancelled", fmt.Errorf("ffmpeg: %w", context.Canceled), true},
		{"caller deadline", fmt.Errorf("ffmpeg: %w", context.DeadlineExceeded), true},
		{"tool not installed", notInstalled, true},
		{"tool rejected the file", errors.New("fpcalc exited 2: could not decode"), false},
		{"unparseable output", errors.New("fpcalc printed no FINGERPRINT= line"), false},
		{"success", nil, false},
	}
	for _, tc := range cases {
		if got := isInconclusive(tc.err); got != tc.want {
			t.Errorf("%s: isInconclusive = %v, want %v", tc.name, got, tc.want)
		}
	}
}

// Either half being inconclusive taints the whole result: storing the half that
// succeeded would stamp the row at the current version with the other half
// NULL, and that NULL would then read as a verdict.
func TestFingerprintResult_InconclusiveIfEitherHalfIs(t *testing.T) {
	stall := fmt.Errorf("fpcalc: %w", errFingerprintTimeout)
	rejected := errors.New("fpcalc exited 2")
	for name, tc := range map[string]struct {
		r    fingerprintResult
		want bool
	}{
		"both succeeded":            {fingerprintResult{streamSHA256: []byte{1}, chromaprint: []int32{1}}, false},
		"hash ok, print stalled":    {fingerprintResult{streamSHA256: []byte{1}, printErr: stall}, true},
		"hash stalled, print ok":    {fingerprintResult{hashErr: stall, chromaprint: []int32{1}}, true},
		"hash ok, print rejected":   {fingerprintResult{streamSHA256: []byte{1}, printErr: rejected}, false},
		"both rejected by the file": {fingerprintResult{hashErr: rejected, printErr: rejected}, false},
	} {
		if got := tc.r.inconclusive(); got != tc.want {
			t.Errorf("%s: inconclusive = %v, want %v", name, got, tc.want)
		}
	}
}