package artifacts

import (
	"errors"
	"os"
	"path/filepath"
	"strings"
	"testing"
	"time"

	"gitea.maximumdirect.net/eric/narratio/internal/artifactpolicy"
	"gitea.maximumdirect.net/eric/narratio/internal/manifest"
)

func TestResolvePreparedInputReturnsVerifiedIdentity(t *testing.T) {
	paths, m, canonicalPath, checksum := preparedInputFixture(t, artifactpolicy.SourceInputSpellCatalog, []byte("{\"spells\":[]}\n"))
	m.Inputs[0].Path = filepath.ToSlash(filepath.Join("inputs", "spell_catalog.json"))

	identity, err := ResolvePreparedInput(paths, m, artifactpolicy.SourceInputSpellCatalog)
	if err != nil {
		t.Fatalf("ResolvePreparedInput() error = %v", err)
	}
	wantAbsolute, err := filepath.Abs(canonicalPath)
	if err != nil {
		t.Fatalf("filepath.Abs() error = %v", err)
	}
	if identity.SourceID != artifactpolicy.SourceInputSpellCatalog ||
		identity.ManifestKind != "spell_catalog" ||
		identity.Path != wantAbsolute ||
		identity.RelativePath != "inputs/spell_catalog.json" ||
		identity.Checksum != checksum ||
		identity.Size != int64(len("{\"spells\":[]}\n")) {
		t.Fatalf("ResolvePreparedInput() = %#v", identity)
	}
}

func TestResolvePreparedInputRequiresCurrentManifestRecord(t *testing.T) {
	paths, _, _, _ := preparedInputFixture(t, artifactpolicy.SourceInputPlayers, []byte("- Alice\n"))

	for _, m := range []*manifest.Manifest{nil, manifest.New("session", time.Now().UTC())} {
		_, err := ResolvePreparedInput(paths, m, artifactpolicy.SourceInputPlayers)
		if !errors.Is(err, ErrPreparedInputAbsent) {
			t.Fatalf("ResolvePreparedInput() error = %v, want ErrPreparedInputAbsent", err)
		}
		var absent *PreparedInputAbsentError
		if !errors.As(err, &absent) || absent.SourceID != artifactpolicy.SourceInputPlayers {
			t.Fatalf("ResolvePreparedInput() error = %#v, want typed players absence", err)
		}
	}
}

func TestResolvePreparedInputRejectsInvalidManifestEvidence(t *testing.T) {
	tests := []struct {
		name    string
		mutate  func(*testing.T, SessionPaths, *manifest.Manifest, string)
		wantErr string
	}{
		{
			name: "duplicate record",
			mutate: func(_ *testing.T, _ SessionPaths, m *manifest.Manifest, _ string) {
				m.Inputs = append(m.Inputs, m.Inputs[0])
			},
			wantErr: "2 manifest records",
		},
		{
			name: "wrong kind",
			mutate: func(_ *testing.T, _ SessionPaths, m *manifest.Manifest, _ string) {
				m.Inputs[0].Kind = "players"
			},
			wantErr: "recorded with manifest kind",
		},
		{
			name: "wrong canonical path",
			mutate: func(t *testing.T, paths SessionPaths, m *manifest.Manifest, _ string) {
				wrong := filepath.Join(paths.InputsDir, "other.json")
				if err := os.WriteFile(wrong, []byte("other\n"), 0o644); err != nil {
					t.Fatalf("WriteFile(wrong) error = %v", err)
				}
				m.Inputs[0].Path = wrong
			},
			wantErr: "does not match canonical path",
		},
		{
			name: "traversal path",
			mutate: func(_ *testing.T, _ SessionPaths, m *manifest.Manifest, _ string) {
				m.Inputs[0].Path = filepath.Join("..", "..", "outside.json")
			},
			wantErr: "outside session root",
		},
		{
			name: "missing checksum",
			mutate: func(_ *testing.T, _ SessionPaths, m *manifest.Manifest, _ string) {
				m.Inputs[0].Checksum = " "
			},
			wantErr: "manifest checksum is required",
		},
		{
			name: "checksum mismatch",
			mutate: func(_ *testing.T, _ SessionPaths, m *manifest.Manifest, _ string) {
				m.Inputs[0].Checksum = strings.Repeat("0", 64)
			},
			wantErr: "checksum mismatch",
		},
	}

	for _, tt := range tests {
		t.Run(tt.name, func(t *testing.T) {
			paths, m, canonicalPath, _ := preparedInputFixture(t, artifactpolicy.SourceInputSpellCatalog, []byte("{\"spells\":[]}\n"))
			tt.mutate(t, paths, m, canonicalPath)
			_, err := ResolvePreparedInput(paths, m, artifactpolicy.SourceInputSpellCatalog)
			if err == nil || !strings.Contains(err.Error(), tt.wantErr) {
				t.Fatalf("ResolvePreparedInput() error = %v, want containing %q", err, tt.wantErr)
			}
		})
	}
}

func TestResolvePreparedInputRejectsInvalidCanonicalFile(t *testing.T) {
	tests := []struct {
		name    string
		mutate  func(*testing.T, string)
		wantErr string
	}{
		{
			name: "missing",
			mutate: func(t *testing.T, path string) {
				if err := os.Remove(path); err != nil {
					t.Fatalf("Remove() error = %v", err)
				}
			},
			wantErr: "open prepared input source",
		},
		{
			name: "symlink",
			mutate: func(t *testing.T, path string) {
				outside := filepath.Join(t.TempDir(), "outside.json")
				if err := os.WriteFile(outside, []byte("outside\n"), 0o644); err != nil {
					t.Fatalf("WriteFile(outside) error = %v", err)
				}
				if err := os.Remove(path); err != nil {
					t.Fatalf("Remove() error = %v", err)
				}
				if err := os.Symlink(outside, path); err != nil {
					t.Fatalf("Symlink() error = %v", err)
				}
			},
			wantErr: "not a regular file",
		},
		{
			name: "directory",
			mutate: func(t *testing.T, path string) {
				if err := os.Remove(path); err != nil {
					t.Fatalf("Remove() error = %v", err)
				}
				if err := os.Mkdir(path, 0o755); err != nil {
					t.Fatalf("Mkdir() error = %v", err)
				}
			},
			wantErr: "not a regular file",
		},
		{
			name: "empty",
			mutate: func(t *testing.T, path string) {
				if err := os.WriteFile(path, nil, 0o644); err != nil {
					t.Fatalf("WriteFile(empty) error = %v", err)
				}
			},
			wantErr: "is empty",
		},
	}

	for _, tt := range tests {
		t.Run(tt.name, func(t *testing.T) {
			paths, m, canonicalPath, _ := preparedInputFixture(t, artifactpolicy.SourceInputSpellCatalog, []byte("{\"spells\":[]}\n"))
			tt.mutate(t, canonicalPath)
			_, err := ResolvePreparedInput(paths, m, artifactpolicy.SourceInputSpellCatalog)
			if err == nil || !strings.Contains(err.Error(), tt.wantErr) {
				t.Fatalf("ResolvePreparedInput() error = %v, want containing %q", err, tt.wantErr)
			}
		})
	}
}

func TestResolvePreparedInputRejectsUnsupportedSource(t *testing.T) {
	paths := buildSessionPaths(t.TempDir(), "campaign", "session")
	_, err := ResolvePreparedInput(paths, nil, "narratio.input.unknown")
	if err == nil || errors.Is(err, ErrPreparedInputAbsent) || !strings.Contains(err.Error(), "unsupported prepared input source") {
		t.Fatalf("ResolvePreparedInput() error = %v", err)
	}
}

func preparedInputFixture(
	t *testing.T,
	sourceID string,
	payload []byte,
) (SessionPaths, *manifest.Manifest, string, string) {
	t.Helper()
	paths := buildSessionPaths(t.TempDir(), "campaign", "session")
	descriptor, ok := artifactpolicy.DescribePreparedInputSource(sourceID)
	if !ok {
		t.Fatalf("DescribePreparedInputSource(%q) ok = false", sourceID)
	}
	canonicalPath := filepath.Join(paths.InputsDir, descriptor.Filename)
	if err := os.MkdirAll(paths.InputsDir, 0o755); err != nil {
		t.Fatalf("MkdirAll(inputs) error = %v", err)
	}
	if err := os.WriteFile(canonicalPath, payload, 0o644); err != nil {
		t.Fatalf("WriteFile(canonical) error = %v", err)
	}
	checksum, err := SHA256File(canonicalPath)
	if err != nil {
		t.Fatalf("SHA256File() error = %v", err)
	}
	m := manifest.New("session", time.Now().UTC())
	m.Inputs = []manifest.InputRecord{{
		Kind:     descriptor.ManifestKind,
		Path:     canonicalPath,
		Checksum: checksum,
		Source:   "campaign_config",
	}}
	return paths, m, canonicalPath, checksum
}