package sources

import (
	"context"
	"os"
	"path/filepath"
	"regexp"
	"testing"
	"time"

	"github.com/go-git/go-git/v5"
	"github.com/go-git/go-git/v5/plumbing"
	"github.com/go-git/go-git/v5/plumbing/object"
	"github.com/stretchr/testify/require"

	"github.com/salvacybersec/keyhunter/pkg/types"
)

func initRepo(t *testing.T) (string, *git.Repository) {
	t.Helper()
	dir := t.TempDir()
	repo, err := git.PlainInit(dir, false)
	require.NoError(t, err)
	return dir, repo
}

func commitFile(t *testing.T, dir string, repo *git.Repository, name, content string) plumbing.Hash {
	t.Helper()
	path := filepath.Join(dir, name)
	require.NoError(t, os.MkdirAll(filepath.Dir(path), 0o755))
	require.NoError(t, os.WriteFile(path, []byte(content), 0o644))
	wt, err := repo.Worktree()
	require.NoError(t, err)
	_, err = wt.Add(name)
	require.NoError(t, err)
	h, err := wt.Commit("add "+name, &git.CommitOptions{
		Author: &object.Signature{Name: "test", Email: "t@x", When: time.Now()},
	})
	require.NoError(t, err)
	return h
}

func drainGit(t *testing.T, src Source) []types.Chunk {
	t.Helper()
	ctx, cancel := context.WithTimeout(context.Background(), 30*time.Second)
	defer cancel()
	out := make(chan types.Chunk, 1024)
	errCh := make(chan error, 1)
	go func() { errCh <- src.Chunks(ctx, out); close(out) }()
	var got []types.Chunk
	for c := range out {
		got = append(got, c)
	}
	require.NoError(t, <-errCh)
	return got
}

func TestGitSource_HistoryWalk(t *testing.T) {
	dir, repo := initRepo(t)
	commitFile(t, dir, repo, "a.txt", "contents alpha")
	commitFile(t, dir, repo, "b.txt", "contents bravo")
	commitFile(t, dir, repo, "c.txt", "contents charlie")

	chunks := drainGit(t, NewGitSource(dir))
	require.GreaterOrEqual(t, len(chunks), 3)

	re := regexp.MustCompile(`^git:[0-9a-f]{7}:.+$`)
	for _, c := range chunks {
		require.Regexp(t, re, c.Source)
	}
}

func TestGitSource_BlobDeduplication(t *testing.T) {
	dir, repo := initRepo(t)
	commitFile(t, dir, repo, "a.txt", "same exact content everywhere")
	commitFile(t, dir, repo, "b.txt", "same exact content everywhere") // identical blob -> same OID
	commitFile(t, dir, repo, "c.txt", "different content here")

	chunks := drainGit(t, NewGitSource(dir))
	// Expect 2 unique blob contents scanned across all commits, not 3 per commit.
	unique := make(map[string]bool)
	for _, c := range chunks {
		unique[string(c.Data)] = true
	}
	require.Len(t, unique, 2, "duplicate blobs must be deduped by OID")
}

func TestGitSource_ModifiedFileKeepsBothVersions(t *testing.T) {
	dir, repo := initRepo(t)
	commitFile(t, dir, repo, "a.txt", "version one")
	commitFile(t, dir, repo, "a.txt", "version two") // modifying produces a second blob

	chunks := drainGit(t, NewGitSource(dir))
	bodies := make(map[string]bool)
	for _, c := range chunks {
		bodies[string(c.Data)] = true
	}
	require.True(t, bodies["version one"], "old version must still be scanned")
	require.True(t, bodies["version two"], "new version must be scanned")
}

func TestGitSource_MultiBranch(t *testing.T) {
	dir, repo := initRepo(t)
	commitFile(t, dir, repo, "base.txt", "base content")

	// Capture current branch to come back to it.
	head, err := repo.Head()
	require.NoError(t, err)
	baseBranch := head.Name()

	// Create and checkout a new branch "feature".
	wt, err := repo.Worktree()
	require.NoError(t, err)
	featureRef := plumbing.NewBranchReferenceName("feature")
	require.NoError(t, wt.Checkout(&git.CheckoutOptions{
		Branch: featureRef,
		Create: true,
	}))
	commitFile(t, dir, repo, "feature_only.txt", "feature branch content")

	// Switch back to base branch and add another file.
	require.NoError(t, wt.Checkout(&git.CheckoutOptions{Branch: baseBranch}))
	commitFile(t, dir, repo, "main_only.txt", "main branch content")

	chunks := drainGit(t, NewGitSource(dir))
	bodies := make(map[string]bool)
	for _, c := range chunks {
		bodies[string(c.Data)] = true
	}
	require.True(t, bodies["base content"], "base blob must be scanned")
	require.True(t, bodies["feature branch content"], "feature branch blob must be scanned")
	require.True(t, bodies["main branch content"], "main branch blob must be scanned")
}

func TestGitSource_TagReachesOldCommit(t *testing.T) {
	dir, repo := initRepo(t)
	oldHash := commitFile(t, dir, repo, "old.txt", "old tagged content")
	// Tag the old commit.
	_, err := repo.CreateTag("v0.1", oldHash, nil)
	require.NoError(t, err)
	// Add more commits after the tag.
	commitFile(t, dir, repo, "new.txt", "later content")

	chunks := drainGit(t, NewGitSource(dir))
	bodies := make(map[string]bool)
	for _, c := range chunks {
		bodies[string(c.Data)] = true
	}
	require.True(t, bodies["old tagged content"], "tagged commit's blobs must be reachable")
	require.True(t, bodies["later content"])
}

func TestGitSource_SinceFilterExcludesAll(t *testing.T) {
	dir, repo := initRepo(t)
	commitFile(t, dir, repo, "a.txt", "alpha")

	src := NewGitSource(dir)
	src.Since = time.Now().Add(1 * time.Hour)
	chunks := drainGit(t, src)
	require.Empty(t, chunks)
}

func TestGitSource_SourceFormat(t *testing.T) {
	dir, repo := initRepo(t)
	commitFile(t, dir, repo, "path/to/file.txt", "some content")

	chunks := drainGit(t, NewGitSource(dir))
	require.NotEmpty(t, chunks)
	re := regexp.MustCompile(`^git:[0-9a-f]{7}:path/to/file\.txt$`)
	matched := false
	for _, c := range chunks {
		if re.MatchString(c.Source) {
			matched = true
			break
		}
	}
	require.True(t, matched, "expected a chunk with source matching git:<sha>:path/to/file.txt")
}

func TestGitSource_MissingRepo(t *testing.T) {
	src := NewGitSource(filepath.Join(t.TempDir(), "not-a-repo"))
	ctx := context.Background()
	out := make(chan types.Chunk, 1)
	err := src.Chunks(ctx, out)
	require.Error(t, err)
}