package cas_test

import (
	"os"
	"path/filepath"
	"sync"
	"testing"

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

	"github.com/gruntwork-io/terragrunt/internal/cas"
	"github.com/gruntwork-io/terragrunt/internal/getter"
	"github.com/gruntwork-io/terragrunt/internal/git"
	"github.com/gruntwork-io/terragrunt/internal/venv"
	"github.com/gruntwork-io/terragrunt/test/helpers"
	"github.com/gruntwork-io/terragrunt/test/helpers/logger"
)

func TestCASCloneByCommitRef(t *testing.T) {
	t.Parallel()

	l := logger.CreateLogger()
	repoURL := startTestServer(t)
	headHash := resolveHead(t, repoURL)

	v := venv.OSVenv()

	t.Run("clone with full commit SHA", func(t *testing.T) {
		t.Parallel()
		tempDir := helpers.TmpDirWOSymlinks(t)

		c, err := cas.New(cas.WithStorePath(filepath.Join(tempDir, "store")))
		require.NoError(t, err)

		targetPath := filepath.Join(tempDir, "repo")
		err = c.Clone(t.Context(), l, v, repoURL, cas.WithDir(targetPath),
			cas.WithBranch(headHash),
			cas.WithDepth(-1))
		require.NoError(t, err)

		_, err = os.Stat(filepath.Join(targetPath, "README.md"))
		require.NoError(t, err)
	})

	t.Run("clone with abbreviated commit SHA", func(t *testing.T) {
		t.Parallel()
		tempDir := helpers.TmpDirWOSymlinks(t)

		c, err := cas.New(cas.WithStorePath(filepath.Join(tempDir, "store")))
		require.NoError(t, err)

		targetPath := filepath.Join(tempDir, "repo")
		err = c.Clone(t.Context(), l, v, repoURL, cas.WithDir(targetPath),
			cas.WithBranch(headHash[:8]),
			cas.WithDepth(-1))
		require.NoError(t, err)

		_, err = os.Stat(filepath.Join(targetPath, "README.md"))
		require.NoError(t, err)
	})

	t.Run("commit ref reuses central store on second clone", func(t *testing.T) {
		t.Parallel()
		tempDir := helpers.TmpDirWOSymlinks(t)
		storePath := filepath.Join(tempDir, "store")

		c, err := cas.New(cas.WithStorePath(storePath))
		require.NoError(t, err)

		// Prime the central git store.
		require.NoError(
			t,
			c.Clone(t.Context(), l, v, repoURL, cas.WithDir(filepath.Join(tempDir, "first")),
				cas.WithBranch(headHash),
				cas.WithDepth(-1)),
		)

		// Drop the test server: a cached clone must not need it.
		repoEntry := cas.EntryPathForURL(filepath.Join(storePath, "git"), repoURL)
		_, err = os.Stat(filepath.Join(repoEntry, "repo"))
		require.NoError(t, err)

		secondClone := filepath.Join(tempDir, "second")
		require.NoError(t, c.Clone(t.Context(), l, v, repoURL, cas.WithDir(secondClone),
			cas.WithBranch(headHash),
			cas.WithDepth(-1)))

		_, err = os.Stat(filepath.Join(secondClone, "README.md"))
		require.NoError(t, err)
	})

	t.Run("unresolvable ref reports no matching reference", func(t *testing.T) {
		t.Parallel()
		tempDir := helpers.TmpDirWOSymlinks(t)

		c, err := cas.New(cas.WithStorePath(filepath.Join(tempDir, "store")))
		require.NoError(t, err)

		err = c.Clone(t.Context(), l, v, repoURL, cas.WithDir(filepath.Join(tempDir, "repo")),
			cas.WithBranch("0000000000000000000000000000000000000000"),
			cas.WithDepth(-1))
		require.Error(t, err)
		assert.ErrorIs(t, err, git.ErrNoMatchingReference)
	})
}

func TestGitStoreEnsureCommit_CachedAfterFirstFetch(t *testing.T) {
	t.Parallel()

	url := startTestServer(t)
	hash := resolveHead(t, url)

	store, v, _ := newTestGitStore(t)
	l := logger.CreateLogger()
	ctx := t.Context()

	// First call must fetch.
	repo, err := store.EnsureCommit(ctx, l, v, url, hash, "")
	require.NoError(t, err)
	assert.Equal(t, hash, repo.Hash)
	assert.NotEmpty(t, repo.Path)
	require.NoError(t, repo.Unlock())

	// Second call hits the local-cache short-circuit.
	repo2, err := store.EnsureCommit(ctx, l, v, url, hash, "")
	require.NoError(t, err)
	assert.Equal(t, hash, repo2.Hash)
	require.NoError(t, repo2.Unlock())
}

func TestGitStoreEnsureCommit_AbbreviatedSHA(t *testing.T) {
	t.Parallel()

	url := startTestServer(t)
	hash := resolveHead(t, url)

	store, v, _ := newTestGitStore(t)
	l := logger.CreateLogger()

	repo, err := store.EnsureCommit(t.Context(), l, v, url, hash[:8], "")
	require.NoError(t, err)
	assert.Equal(t, hash, repo.Hash, "abbreviated SHA must canonicalize to the full hash")
	require.NoError(t, repo.Unlock())
}

func TestGitStoreEnsureCommit_UnresolvableSurfacesNoMatchingReference(t *testing.T) {
	t.Parallel()

	url := startTestServer(t)

	store, v, _ := newTestGitStore(t)
	l := logger.CreateLogger()

	_, err := store.EnsureCommit(
		t.Context(),
		l,
		v,
		url,
		"0000000000000000000000000000000000000000",
		"",
	)
	require.Error(t, err)
	assert.ErrorIs(t, err, git.ErrNoMatchingReference)
}

// TestCASClone_NonTipCommit pins the actual reason this feature
// exists: cloning a commit that is not the tip of any branch. With
// the previous --depth 1 path the fetch would have failed; the new
// commit-fallback flow does a full-history fetch so older commits
// remain reachable.
func TestCASClone_NonTipCommit(t *testing.T) {
	t.Parallel()

	srv := newEmptyTestServer(t)
	require.NoError(t, srv.CommitFile(t.Context(), "first.txt", []byte("first"), "first commit"))

	firstHash, err := srv.Head(t.Context())
	require.NoError(t, err)

	require.NoError(t, srv.CommitFile(t.Context(), "second.txt", []byte("second"), "second commit"))
	require.NoError(t, srv.CommitFile(t.Context(), "third.txt", []byte("third"), "third commit"))

	headHash, err := srv.Head(t.Context())
	require.NoError(t, err)
	require.NotEqual(t, firstHash, headHash, "non-tip test requires HEAD to differ from target")

	repoURL, err := srv.Start(t.Context())
	require.NoError(t, err)

	tempDir := helpers.TmpDirWOSymlinks(t)

	c, err := cas.New(cas.WithStorePath(filepath.Join(tempDir, "store")))
	require.NoError(t, err)

	v := venv.OSVenv()

	targetPath := filepath.Join(tempDir, "repo")
	err = c.Clone(t.Context(), logger.CreateLogger(), v, repoURL, cas.WithDir(targetPath),
		cas.WithBranch(firstHash),
		cas.WithDepth(-1))
	require.NoError(t, err)

	// Only the first commit's file should be present; later commits
	// belong to descendants we did not check out.
	_, err = os.Stat(filepath.Join(targetPath, "first.txt"))
	require.NoError(t, err)

	_, err = os.Stat(filepath.Join(targetPath, "second.txt"))
	require.Error(t, err, "non-tip clone must not include later commits")
}

// TestCASClone_AbbreviatedHexBranchAdvancesAcrossClones pins that a
// branch whose name happens to be a hex prefix of its own tip is not
// frozen at the first-fetched tip on subsequent clones. The probe in
// resolveReference shells out to git rev-parse against the per-URL
// bare repo, which resolves ref names ahead of object hashes; before
// the looksLikeFullSHA tightening, an abbreviated hex branch name
// (e.g. the first 8 chars of its own tip) would pass the probe's
// prefix check and short-circuit ls-remote, so the branch would
// appear stuck at the cached commit even after the server-side tip
// moved on.
func TestCASClone_AbbreviatedHexBranchAdvancesAcrossClones(t *testing.T) {
	t.Parallel()

	srv := newEmptyTestServer(t)
	require.NoError(t, srv.CommitFile(t.Context(), "v1.txt", []byte("v1"), "first"))

	firstHash, err := srv.Head(t.Context())
	require.NoError(t, err)

	// Branch name is the 8-char prefix of its own tip: the worst case
	// for the probe's prefix check.
	branch := firstHash[:8]
	require.NoError(t, srv.Branch(t.Context(), branch))

	repoURL, err := srv.Start(t.Context())
	require.NoError(t, err)

	tempDir := helpers.TmpDirWOSymlinks(t)
	storePath := filepath.Join(tempDir, "store")

	c, err := cas.New(cas.WithStorePath(storePath))
	require.NoError(t, err)

	v := venv.OSVenv()

	l := logger.CreateLogger()

	require.NoError(
		t,
		c.Clone(t.Context(), l, v, repoURL, cas.WithDir(filepath.Join(tempDir, "first")),
			cas.WithBranch(branch),
			cas.WithDepth(-1)),
	)

	// Advance the branch to a new commit. ls-remote must see the new
	// tip on the second clone; the probe would otherwise serve the
	// stale cached commit.
	require.NoError(t, srv.CommitFile(t.Context(), "v2.txt", []byte("v2"), "second"))
	require.NoError(t, srv.Branch(t.Context(), branch))

	secondDir := filepath.Join(tempDir, "second")
	require.NoError(t, c.Clone(t.Context(), l, v, repoURL, cas.WithDir(secondDir),
		cas.WithBranch(branch),
		cas.WithDepth(-1)))

	_, err = os.Stat(filepath.Join(secondDir, "v2.txt"))
	require.NoError(
		t,
		err,
		"second clone must reflect the moved branch tip, not the cached prefix-matching commit",
	)
}

// TestCASClone_HexBranchNameResolvesViaLsRemote verifies that a
// branch whose name happens to be 40 lowercase hex characters still
// resolves through ls-remote rather than being treated as a commit
// SHA. The branch is intentionally named with a hash that does not
// match any commit so commit-fallback resolution would fail, leaving
// ls-remote as the only path to success.
func TestCASClone_HexBranchNameResolvesViaLsRemote(t *testing.T) {
	t.Parallel()

	srv := newEmptyTestServer(t)
	require.NoError(t, srv.CommitFile(t.Context(), "README.md", []byte("# test"), "initial"))

	const hexBranch = "aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa"
	require.NoError(t, srv.Branch(t.Context(), hexBranch))

	repoURL, err := srv.Start(t.Context())
	require.NoError(t, err)

	tempDir := helpers.TmpDirWOSymlinks(t)

	c, err := cas.New(cas.WithStorePath(filepath.Join(tempDir, "store")))
	require.NoError(t, err)

	v := venv.OSVenv()

	targetPath := filepath.Join(tempDir, "repo")
	err = c.Clone(t.Context(), logger.CreateLogger(), v, repoURL, cas.WithDir(targetPath),
		cas.WithBranch(hexBranch),
		cas.WithDepth(-1))
	require.NoError(t, err)

	_, err = os.Stat(filepath.Join(targetPath, "README.md"))
	require.NoError(t, err)
}

// TestCASClone_TagRef pins that ls-remote-resolved tag refs continue
// to work after the commit-fallback wiring landed.
func TestCASClone_TagRef(t *testing.T) {
	t.Parallel()

	srv := newEmptyTestServer(t)
	require.NoError(t, srv.CommitFile(t.Context(), "README.md", []byte("# tagged"), "initial"))
	require.NoError(t, srv.Tag(t.Context(), "v1.0.0"))

	repoURL, err := srv.Start(t.Context())
	require.NoError(t, err)

	tempDir := helpers.TmpDirWOSymlinks(t)

	c, err := cas.New(cas.WithStorePath(filepath.Join(tempDir, "store")))
	require.NoError(t, err)

	v := venv.OSVenv()

	targetPath := filepath.Join(tempDir, "repo")
	err = c.Clone(t.Context(), logger.CreateLogger(), v, repoURL, cas.WithDir(targetPath),
		cas.WithBranch("v1.0.0"),
		cas.WithDepth(-1))
	require.NoError(t, err)

	_, err = os.Stat(filepath.Join(targetPath, "README.md"))
	require.NoError(t, err)
}

// TestGitStoreEnsureCommit_TagOnlyCommit pins the regression where the
// fallback fetch only pulled refs/heads/*, so a commit reachable only
// via an annotated tag stayed missing and surfaced as
// ErrNoMatchingReference. The fix broadens the refspec so tag-only
// commits arrive on the first fetch.
func TestGitStoreEnsureCommit_TagOnlyCommit(t *testing.T) {
	t.Parallel()

	srv := newEmptyTestServer(t)

	require.NoError(t, srv.CommitFile(t.Context(), "first.txt", []byte("first"), "first commit"))

	firstHash, err := srv.Head(t.Context())
	require.NoError(t, err)

	require.NoError(t, srv.CommitFile(t.Context(), "tagged.txt", []byte("tagged"), "tagged commit"))

	taggedHash, err := srv.Head(t.Context())
	require.NoError(t, err)
	require.NotEqual(t, firstHash, taggedHash, "tagged commit must differ from first commit")

	require.NoError(t, srv.Tag(t.Context(), "v1"))

	// Rewind main past the tagged commit so it is reachable only via the tag.
	require.NoError(t, srv.SetBranch(t.Context(), "main", firstHash))

	repoURL, err := srv.Start(t.Context())
	require.NoError(t, err)

	store, fs, _ := newTestGitStore(t)
	l := logger.CreateLogger()
	ctx := t.Context()

	t.Run("rev-parse fallback", func(t *testing.T) {
		t.Parallel()

		repo, err := store.EnsureCommit(ctx, l, fs, repoURL, taggedHash, "")
		require.NoError(t, err)
		assert.Equal(t, taggedHash, repo.Hash)
		require.NoError(t, repo.Unlock())
	})

	t.Run("known-hash fallback", func(t *testing.T) {
		t.Parallel()

		store2, fs2, _ := newTestGitStore(t)
		repo, err := store2.EnsureCommit(ctx, l, fs2, repoURL, taggedHash, taggedHash)
		require.NoError(t, err)
		assert.Equal(t, taggedHash, repo.Hash)
		require.NoError(t, repo.Unlock())
	})
}

// TestGitStoreEnsureCommit_OfflineWhenCached proves that once a
// commit is cached in the central git store, EnsureCommit resolves it
// without touching the network. We tear the server down between the
// priming call and the cached call to make any accidental fetch
// explicit.
func TestGitStoreEnsureCommit_OfflineWhenCached(t *testing.T) {
	t.Parallel()

	srv := newEmptyTestServer(t)
	require.NoError(t, srv.CommitFile(t.Context(), "README.md", []byte("# offline"), "initial"))

	hash, err := srv.Head(t.Context())
	require.NoError(t, err)

	repoURL, err := srv.Start(t.Context())
	require.NoError(t, err)

	store, v, _ := newTestGitStore(t)
	l := logger.CreateLogger()
	ctx := t.Context()

	primed, err := store.EnsureCommit(ctx, l, v, repoURL, hash, "")
	require.NoError(t, err)
	require.NoError(t, primed.Unlock())

	require.NoError(t, srv.Close())

	cached, err := store.EnsureCommit(ctx, l, v, repoURL, hash, "")
	require.NoError(t, err, "cached commit must resolve without contacting the server")
	assert.Equal(t, hash, cached.Hash)
	require.NoError(t, cached.Unlock())
}

// TestGitStoreEnsureCommit_KnownHashFastPath pins the knownHash
// branch: when the caller has already canonicalized rawRef via
// ProbeCachedCommit, EnsureCommit verifies presence with HasObject
// and skips rev-parse. The server is dropped after priming so any
// accidental fetch surfaces as a failure.
func TestGitStoreEnsureCommit_KnownHashFastPath(t *testing.T) {
	t.Parallel()

	srv := newEmptyTestServer(t)
	require.NoError(t, srv.CommitFile(t.Context(), "README.md", []byte("# fast path"), "initial"))

	hash, err := srv.Head(t.Context())
	require.NoError(t, err)

	repoURL, err := srv.Start(t.Context())
	require.NoError(t, err)

	store, fs, _ := newTestGitStore(t)
	l := logger.CreateLogger()
	ctx := t.Context()

	primed, err := store.EnsureCommit(ctx, l, fs, repoURL, hash, "")
	require.NoError(t, err)
	require.NoError(t, primed.Unlock())

	require.NoError(t, srv.Close())

	cached, err := store.EnsureCommit(ctx, l, fs, repoURL, hash, hash)
	require.NoError(t, err, "knownHash path must resolve without contacting the server")
	assert.Equal(t, hash, cached.Hash)
	require.NoError(t, cached.Unlock())
}

// TestCASClone_OfflineWhenCommitCached pins offline behavior for
// previously-cached commit refs: once a SHA has been cloned, a
// subsequent clone for the same SHA must succeed even when the
// remote is unreachable. The test server is shut down between the
// priming and the cached call so any ls-remote call would surface as
// a clone failure.
func TestCASClone_OfflineWhenCommitCached(t *testing.T) {
	t.Parallel()

	srv := newEmptyTestServer(t)
	require.NoError(
		t,
		srv.CommitFile(t.Context(), "README.md", []byte("# offline cached"), "initial"),
	)

	hash, err := srv.Head(t.Context())
	require.NoError(t, err)

	repoURL, err := srv.Start(t.Context())
	require.NoError(t, err)

	tempDir := helpers.TmpDirWOSymlinks(t)
	storePath := filepath.Join(tempDir, "store")

	c, err := cas.New(cas.WithStorePath(storePath))
	require.NoError(t, err)

	v := venv.OSVenv()

	l := logger.CreateLogger()

	require.NoError(
		t,
		c.Clone(t.Context(), l, v, repoURL, cas.WithDir(filepath.Join(tempDir, "primed")),
			cas.WithBranch(hash),
			cas.WithDepth(-1)),
	)

	require.NoError(t, srv.Close())

	cachedDir := filepath.Join(tempDir, "cached")
	require.NoError(t, c.Clone(t.Context(), l, v, repoURL, cas.WithDir(cachedDir),
		cas.WithBranch(hash),
		cas.WithDepth(-1)), "cached commit ref must resolve without contacting the server")

	_, err = os.Stat(filepath.Join(cachedDir, "README.md"))
	require.NoError(t, err)
}

// TestCASGetterGet_WithCommitRef exercises the full URL-parsing path
// through CASGetter for a ref=<sha> query string.
func TestCASGetterGet_WithCommitRef(t *testing.T) {
	t.Parallel()

	repoURL := startTestServer(t)
	headHash := resolveHead(t, repoURL)

	tempDir := helpers.TmpDirWOSymlinks(t)
	storePath := filepath.Join(tempDir, "store")

	c, err := cas.New(cas.WithStorePath(storePath))
	require.NoError(t, err)

	v := venv.OSVenv()

	g := getter.NewCASGetter(logger.CreateLogger(), c, v, &cas.CloneOptions{Depth: -1})
	client := getter.Client{Getters: []getter.Getter{g}}

	dst := filepath.Join(tempDir, "repo")

	res, err := client.Get(t.Context(), &getter.Request{
		Src: "git::" + repoURL + "?ref=" + headHash,
		Dst: dst,
	})
	require.NoError(t, err)
	assert.Equal(t, dst, res.Dst)

	_, err = os.Stat(filepath.Join(dst, "README.md"))
	require.NoError(t, err)
}

// TestCAS_CommitRefFallbackWhenGitStoreFails mirrors
// TestCAS_FallbackWhenGitStoreFails for the commit-fallback path: if
// the central git store cannot create its per-URL directory, the
// commit-ref clone falls back to a temporary bare clone (no --depth)
// and resolves the SHA there.
func TestCAS_CommitRefFallbackWhenGitStoreFails(t *testing.T) {
	t.Parallel()

	repoURL := startTestServer(t)
	headHash := resolveHead(t, repoURL)

	tempDir := helpers.TmpDirWOSymlinks(t)
	storePath := filepath.Join(tempDir, "store")

	gitStoreRoot := filepath.Join(storePath, "git")
	require.NoError(t, os.MkdirAll(gitStoreRoot, 0o755))

	blocker := cas.EntryPathForURL(gitStoreRoot, repoURL)
	require.NoError(t, os.WriteFile(blocker, []byte("not a directory"), 0o644))

	c, err := cas.New(cas.WithStorePath(storePath))
	require.NoError(t, err)

	v := venv.OSVenv()

	targetPath := filepath.Join(tempDir, "repo")
	err = c.Clone(t.Context(), logger.CreateLogger(), v, repoURL, cas.WithDir(targetPath),
		cas.WithBranch(headHash),
		cas.WithDepth(-1))
	require.NoError(t, err)

	_, err = os.Stat(filepath.Join(targetPath, "README.md"))
	require.NoError(t, err)

	info, err := os.Stat(blocker)
	require.NoError(t, err)
	assert.False(t, info.IsDir(), "fallback must not have replaced the blocking file")
}

func TestCASCloneByCommitRefConcurrentWithRacing(t *testing.T) {
	t.Parallel()

	l := logger.CreateLogger()
	repoURL := startTestServer(t)
	headHash := resolveHead(t, repoURL)

	tempDir := helpers.TmpDirWOSymlinks(t)
	storePath := filepath.Join(tempDir, "store")

	c, err := cas.New(cas.WithStorePath(storePath))
	require.NoError(t, err)

	v := venv.OSVenv()

	const workers = 4

	var wg sync.WaitGroup

	errs := make([]error, workers)

	for i := range workers {
		wg.Add(1)

		go func(idx int) {
			defer wg.Done()

			errs[idx] = c.Clone(t.Context(), l, v, repoURL,
				cas.WithDir(filepath.Join(tempDir, "repo", "worker", string(rune('a'+idx)))),
				cas.WithBranch(headHash),
				cas.WithDepth(-1))
		}(i)
	}

	wg.Wait()

	for i, e := range errs {
		require.NoErrorf(t, e, "worker %d", i)
	}
}
