package core

import (
	"os"
	"path/filepath"
	"regexp"
	"testing"
)

func TestLinkFile(t *testing.T) {
	tmp := t.TempDir()

	src := filepath.Join(tmp, "source.txt")
	dst := filepath.Join(tmp, "link.txt")

	// Create source file
	if err := os.WriteFile(src, []byte("hello"), 0o644); err != nil {
		t.Fatalf("failed to create source: %v", err)
	}

	// Test: create symlink
	if err := LinkFile(src, dst); err != nil {
		t.Errorf("LinkFile failed: %v", err)
	}

	// Verify symlink
	info, err := os.Lstat(dst)
	if err != nil {
		t.Fatalf("failed to stat link: %v", err)
	}
	if info.Mode()&os.ModeSymlink == 0 {
		t.Error("dst is not a symlink")
	}

	// Test: idempotent - same symlink again should succeed
	if err := LinkFile(src, dst); err != nil {
		t.Errorf("LinkFile second time failed: %v", err)
	}

	// Test: conflict - different source should error
	src2 := filepath.Join(tmp, "source2.txt")
	if err := os.WriteFile(src2, []byte("world"), 0o644); err != nil {
		t.Fatalf("failed to create source2: %v", err)
	}

	if err := LinkFile(src2, dst); err == nil {
		t.Error("LinkFile should fail with conflicting symlink")
	}

	// Test: conflict - non-symlink file should error
	dst2 := filepath.Join(tmp, "regular.txt")
	if err := os.WriteFile(dst2, []byte("content"), 0o644); err != nil {
		t.Fatalf("failed to create regular file: %v", err)
	}

	if err := LinkFile(src, dst2); err == nil {
		t.Error("LinkFile should fail when target exists and is not a symlink")
	}
}

func TestFindStaleLinks(t *testing.T) {
	tmp := t.TempDir()
	filesDir := filepath.Join(tmp, "files")
	targetDir := filepath.Join(tmp, "target")

	if err := os.MkdirAll(filesDir, 0o755); err != nil {
		t.Fatalf("failed to create files dir: %v", err)
	}
	if err := os.MkdirAll(targetDir, 0o755); err != nil {
		t.Fatalf("failed to create target dir: %v", err)
	}

	// Create a file in files/
	src := filepath.Join(filesDir, "test.txt")
	if err := os.WriteFile(src, []byte("content"), 0o644); err != nil {
		t.Fatalf("failed to create source: %v", err)
	}

	// Create a subdirectory with a file
	subDir := filepath.Join(filesDir, "subdir")
	if err := os.MkdirAll(subDir, 0o755); err != nil {
		t.Fatalf("failed to create subdir: %v", err)
	}
	src2 := filepath.Join(subDir, "nested.txt")
	if err := os.WriteFile(src2, []byte("nested"), 0o644); err != nil {
		t.Fatalf("failed to create nested source: %v", err)
	}

	// Create symlinks
	dst := filepath.Join(targetDir, "test.txt")
	if err := os.Symlink(src, dst); err != nil {
		t.Fatalf("failed to create symlink: %v", err)
	}

	targetSubDir := filepath.Join(targetDir, "subdir")
	if err := os.MkdirAll(targetSubDir, 0o755); err != nil {
		t.Fatalf("failed to create target subdir: %v", err)
	}
	dst2 := filepath.Join(targetSubDir, "nested.txt")
	if err := os.Symlink(src2, dst2); err != nil {
		t.Fatalf("failed to create nested symlink: %v", err)
	}

	// Test: no stale links when sources exist
	stale, err := FindStaleLinks(filesDir, targetDir)
	if err != nil {
		t.Errorf("FindStaleLinks failed: %v", err)
	}
	if len(stale) != 0 {
		t.Errorf("expected 0 stale links, got %d", len(stale))
	}

	// Note: The current implementation walks filesDir, so it can't detect
	// stale links for files that have been deleted from the repo.
	// This is a known limitation - we'd need to walk the target directory
	// to find orphaned symlinks, but that has performance issues with
	// large target directories (like ~).
}

func TestFindStaleLinks_IgnoresNonRepoSymlinks(t *testing.T) {
	tmp := t.TempDir()
	filesDir := filepath.Join(tmp, "files")
	targetDir := filepath.Join(tmp, "target")

	if err := os.MkdirAll(filesDir, 0o755); err != nil {
		t.Fatalf("failed to create files dir: %v", err)
	}
	if err := os.MkdirAll(targetDir, 0o755); err != nil {
		t.Fatalf("failed to create target dir: %v", err)
	}

	// Create a file outside the repo
	external := filepath.Join(tmp, "external.txt")
	if err := os.WriteFile(external, []byte("external"), 0o644); err != nil {
		t.Fatalf("failed to create external file: %v", err)
	}

	// Create a symlink to external file (should be ignored by FindStaleLinks)
	dst := filepath.Join(targetDir, "link.txt")
	if err := os.Symlink(external, dst); err != nil {
		t.Fatalf("failed to create symlink: %v", err)
	}

	// Test: should not report external symlinks as stale
	stale, err := FindStaleLinks(filesDir, targetDir)
	if err != nil {
		t.Errorf("FindStaleLinks failed: %v", err)
	}
	if len(stale) != 0 {
		t.Errorf("expected 0 stale links (external symlinks ignored), got %d", len(stale))
	}
}

func TestApplyPackage(t *testing.T) {
	tmp := t.TempDir()
	filesDir := filepath.Join(tmp, "files")
	targetDir := filepath.Join(tmp, "target")

	// Create files structure
	subDir := filepath.Join(filesDir, "config")
	if err := os.MkdirAll(subDir, 0o755); err != nil {
		t.Fatalf("failed to create subdir: %v", err)
	}

	file1 := filepath.Join(filesDir, "readme.txt")
	if err := os.WriteFile(file1, []byte("readme"), 0o644); err != nil {
		t.Fatalf("failed to create file1: %v", err)
	}

	file2 := filepath.Join(subDir, "app.conf")
	if err := os.WriteFile(file2, []byte("config"), 0o644); err != nil {
		t.Fatalf("failed to create file2: %v", err)
	}

	cfg := &packageConfig{} // empty config, no ignores

	// Apply package
	if err := ApplyPackage(filesDir, targetDir, cfg); err != nil {
		t.Errorf("ApplyPackage failed: %v", err)
	}

	// Verify symlinks exist
	targetFile1 := filepath.Join(targetDir, "readme.txt")
	info, err := os.Lstat(targetFile1)
	if err != nil {
		t.Errorf("target file1 not found: %v", err)
	} else if info.Mode()&os.ModeSymlink == 0 {
		t.Error("target file1 is not a symlink")
	}

	targetFile2 := filepath.Join(targetDir, "config", "app.conf")
	info, err = os.Lstat(targetFile2)
	if err != nil {
		t.Errorf("target file2 not found: %v", err)
	} else if info.Mode()&os.ModeSymlink == 0 {
		t.Error("target file2 is not a symlink")
	}

	// Verify content is accessible through symlink
	content, err := os.ReadFile(targetFile1)
	if err != nil {
		t.Errorf("failed to read through symlink: %v", err)
	}
	if string(content) != "readme" {
		t.Errorf("wrong content through symlink: %s", string(content))
	}
}

func TestApplyPackage_WithIgnores(t *testing.T) {
	tmp := t.TempDir()
	filesDir := filepath.Join(tmp, "files")
	targetDir := filepath.Join(tmp, "target")

	if err := os.MkdirAll(filesDir, 0o755); err != nil {
		t.Fatalf("failed to create files dir: %v", err)
	}

	// Create files, some to be ignored
	mainFile := filepath.Join(filesDir, "main.txt")
	if err := os.WriteFile(mainFile, []byte("main"), 0o644); err != nil {
		t.Fatalf("failed to create main file: %v", err)
	}

	cacheDir := filepath.Join(filesDir, "cache")
	if err := os.MkdirAll(cacheDir, 0o755); err != nil {
		t.Fatalf("failed to create cache dir: %v", err)
	}
	cacheFile := filepath.Join(cacheDir, "data.tmp")
	if err := os.WriteFile(cacheFile, []byte("temp"), 0o644); err != nil {
		t.Fatalf("failed to create cache file: %v", err)
	}

	// Create config with ignore pattern
	cfg := &packageConfig{
		compiledIgnores: []*regexp.Regexp{},
	}
	re, _ := GlobToRegexp("cache/**")
	cfg.compiledIgnores = append(cfg.compiledIgnores, re)

	// Apply package
	if err := ApplyPackage(filesDir, targetDir, cfg); err != nil {
		t.Errorf("ApplyPackage failed: %v", err)
	}

	// Verify main file is linked
	targetMain := filepath.Join(targetDir, "main.txt")
	if _, err := os.Lstat(targetMain); err != nil {
		t.Errorf("main file should be linked: %v", err)
	}

	// Verify cache file is not linked (the directory may exist since we walk it
	// before checking ignore patterns, but it should be empty)
	targetCacheFile := filepath.Join(targetDir, "cache", "data.tmp")
	if _, err := os.Lstat(targetCacheFile); !os.IsNotExist(err) {
		t.Error("cache/data.tmp should not exist in target")
	}
}

func TestRestoreOne(t *testing.T) {
	tmp := t.TempDir()
	filesDir := filepath.Join(tmp, "files")
	targetDir := filepath.Join(tmp, "target")

	if err := os.MkdirAll(filesDir, 0o755); err != nil {
		t.Fatalf("failed to create files dir: %v", err)
	}
	if err := os.MkdirAll(targetDir, 0o755); err != nil {
		t.Fatalf("failed to create target dir: %v", err)
	}

	// Create source file in repo
	src := filepath.Join(filesDir, "test.txt")
	if err := os.WriteFile(src, []byte("original"), 0o644); err != nil {
		t.Fatalf("failed to create source: %v", err)
	}

	// Create symlink in target
	dst := filepath.Join(targetDir, "test.txt")
	if err := os.Symlink(src, dst); err != nil {
		t.Fatalf("failed to create symlink: %v", err)
	}

	// Restore (removes symlink, copies file)
	filesAbs, _ := filepath.Abs(filesDir)
	if err := RestoreOne(src, dst, filesAbs, false); err != nil {
		t.Errorf("RestoreOne failed: %v", err)
	}

	// Verify symlink is gone
	info, err := os.Lstat(dst)
	if err != nil {
		t.Fatalf("failed to stat restored file: %v", err)
	}
	if info.Mode()&os.ModeSymlink != 0 {
		t.Error("file should not be a symlink after restore")
	}

	// Verify content is preserved
	content, err := os.ReadFile(dst)
	if err != nil {
		t.Errorf("failed to read restored file: %v", err)
	}
	if string(content) != "original" {
		t.Errorf("wrong content after restore: %s", string(content))
	}
}