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package oswrapper_test

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

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

// Tests for the Remove() function in FSTestOSWrapper.

// NOTE: There are two types of tests in this file, those suffixed with _MatchesReal and those that
// are not. Those that are suffixed are meant to be testing the behaviour of the FSTestOSWrapper
// against the RealOSWrapper to confirm that it is a drop in replacement. Those that are not
// suffixed are traditional unittests that test the implementation functions in isolation against
// defined expectations.

func TestFSTestOSWrapper_Remove(t *testing.T) {
	root := getTestRoot()
	tests := []struct {
		name          string
		setup         unittestSetup
		path          string
		expectMissing []string
		expectPresent []string
		expectedError
	}{
		{
			name: "Remove file",
			path: filepath.Join(root, "file.txt"),
			setup: unittestSetup{
				initialFiles: map[string]string{filepath.Join(root, "file.txt"): "content"},
			},
			expectMissing: []string{filepath.Join(root, "file.txt")},
		},
		{
			name: "Remove empty directory",
			path: filepath.Join(root, "emptydir"),
			setup: unittestSetup{
				initialDirs: []string{filepath.Join(root, "emptydir")},
			},
			expectMissing: []string{filepath.Join(root, "emptydir")},
		},
		{
			name: "Remove file, others retained",
			path: filepath.Join(root, "file.txt"),
			setup: unittestSetup{
				initialFiles: map[string]string{
					filepath.Join(root, "file.txt"):     "content",
					filepath.Join(root, "other.txt"):    "other content",
					filepath.Join(root, "dir", "f.txt"): "in dir",
				},
				initialDirs: []string{filepath.Join(root, "otherdir")},
			},
			expectMissing: []string{filepath.Join(root, "file.txt")},
			expectPresent: []string{
				filepath.Join(root, "other.txt"),
				filepath.Join(root, "otherdir"),
				filepath.Join(root, "dir"),
				filepath.Join(root, "dir", "f.txt"),
			},
		},
		{
			name: "Error on non-existent path",
			path: filepath.Join(root, "nonexistent"),
			expectedError: expectedError{
				wantErrIs: os.ErrNotExist,
			},
		},
		{
			name: "Error on non-empty directory",
			path: filepath.Join(root, "nonemptydir"),
			setup: unittestSetup{
				initialFiles: map[string]string{filepath.Join(root, "nonemptydir", "file.txt"): "content"},
				initialDirs:  []string{filepath.Join(root, "nonemptydir")},
			},
			expectPresent: []string{
				filepath.Join(root, "nonemptydir"),
				filepath.Join(root, "nonemptydir", "file.txt"),
			},
			expectedError: expectedError{
				wantErrIs: syscall.ENOTEMPTY,
			},
		},
		{
			name: "Remove symlink to file",
			path: filepath.Join(root, "link_to_file"),
			setup: unittestSetup{
				initialFiles:    map[string]string{filepath.Join(root, "file.txt"): "content"},
				initialSymlinks: map[string]string{filepath.Join(root, "link_to_file"): filepath.Join(root, "file.txt")},
			},
			expectMissing: []string{filepath.Join(root, "link_to_file")},
			expectPresent: []string{filepath.Join(root, "file.txt")},
		},
		{
			name: "Remove symlink to directory",
			path: filepath.Join(root, "link_to_dir"),
			setup: unittestSetup{
				initialDirs:     []string{filepath.Join(root, "dir")},
				initialSymlinks: map[string]string{filepath.Join(root, "link_to_dir"): filepath.Join(root, "dir")},
			},
			expectMissing: []string{filepath.Join(root, "link_to_dir")},
			expectPresent: []string{filepath.Join(root, "dir")},
		},
		{
			name: "Remove file inside symlinked directory",
			path: filepath.Join(root, "link_to_dir", "file.txt"),
			setup: unittestSetup{
				initialFiles:    map[string]string{filepath.Join(root, "dir", "file.txt"): "content"},
				initialSymlinks: map[string]string{filepath.Join(root, "link_to_dir"): filepath.Join(root, "dir")},
			},
			expectMissing: []string{
				filepath.Join(root, "link_to_dir", "file.txt"),
				filepath.Join(root, "dir", "file.txt"),
			},
		},
		{
			name: "Remove broken symlink",
			path: filepath.Join(root, "broken_link"),
			setup: unittestSetup{
				initialSymlinks: map[string]string{filepath.Join(root, "broken_link"): "nonexistent"},
			},
			expectMissing: []string{filepath.Join(root, "broken_link")},
		},
		{
			name: "Remove symlink loop",
			path: filepath.Join(root, "loop1"),
			setup: unittestSetup{
				initialSymlinks: map[string]string{
					filepath.Join(root, "loop1"): filepath.Join(root, "loop2"),
					filepath.Join(root, "loop2"): filepath.Join(root, "loop1"),
				},
			},
			expectMissing: []string{filepath.Join(root, "loop1"), filepath.Join(root, "loop2")},
		},
		{
			name: "Error removing path with symlink loop in parent",
			path: filepath.Join(root, "loop1", "file.txt"),
			setup: unittestSetup{
				initialSymlinks: map[string]string{
					filepath.Join(root, "loop1"): filepath.Join(root, "loop2"),
					filepath.Join(root, "loop2"): filepath.Join(root, "loop1"),
				},
			},
			expectedError: expectedError{
				wantErrIs: syscall.ELOOP,
			},
		},
		{
			name: "Error removing path with broken symlink in parent",
			path: filepath.Join(root, "broken_link", "file.txt"),
			setup: unittestSetup{
				initialSymlinks: map[string]string{filepath.Join(root, "broken_link"): "nonexistent"},
			},
			expectedError: expectedError{
				wantErrIs: os.ErrNotExist,
			},
		},
	}

	for _, tc := range tests {
		t.Run(tc.name, func(t *testing.T) {
			wrapper := tc.setup.setup(t)
			err := wrapper.Remove(tc.path)

			for _, p := range tc.expectPresent {
				_, statErr := wrapper.Stat(p)
				require.NoError(t, statErr, "path '%s' should exist but it does not", p)
			}

			if tc.expectedError.Check(t, err) {
				return
			}

			for _, p := range tc.expectMissing {
				_, statErr := wrapper.Stat(p)
				require.Error(t, statErr, "path '%s' should not exist but it does", p)
				require.True(t, os.IsNotExist(statErr))
			}
		})
	}
}

func TestFSTestOSWrapper_Remove_MatchesReal(t *testing.T) {
	tests := []struct {
		name         string
		setup        matchesRealSetup
		pathToRemove string
	}{
		{
			name: "Remove file",
			setup: matchesRealSetup{unittestSetup{
				initialFiles: map[string]string{"file.txt": "content"},
			}},
			pathToRemove: "file.txt",
		},
		{
			name: "Remove file, others retained",
			setup: matchesRealSetup{unittestSetup{
				initialFiles: map[string]string{
					"file.txt":                    "content",
					"other.txt":                   "other content",
					filepath.Join("dir", "f.txt"): "in dir",
				},
				initialDirs: []string{
					"dir",
					"otherdir",
				},
			}},
			pathToRemove: "file.txt",
		},
		{
			name: "Remove empty directory",
			setup: matchesRealSetup{unittestSetup{
				initialDirs: []string{"emptydir"},
			}},
			pathToRemove: "emptydir",
		},
		{
			name:         "Error on non-existent path",
			pathToRemove: "nonexistent",
		},
		{
			name: "Error on non-empty directory",
			setup: matchesRealSetup{unittestSetup{
				initialFiles: map[string]string{filepath.Join("dir", "file.txt"): "content"},
				initialDirs:  []string{"dir"},
			}},
			pathToRemove: "dir",
		},
		{
			name: "Remove symlink to file",
			setup: matchesRealSetup{unittestSetup{
				initialFiles:    map[string]string{"file.txt": "content"},
				initialSymlinks: map[string]string{"link_to_file": "file.txt"},
			}},
			pathToRemove: "link_to_file",
		},
		{
			name: "Remove symlink to directory",
			setup: matchesRealSetup{unittestSetup{
				initialDirs:     []string{"dir"},
				initialSymlinks: map[string]string{"link_to_dir": "dir"},
			}},
			pathToRemove: "link_to_dir",
		},
		{
			name: "Remove file inside symlinked directory",
			setup: matchesRealSetup{unittestSetup{
				initialFiles:    map[string]string{filepath.Join("dir", "file.txt"): "content"},
				initialSymlinks: map[string]string{"link_to_dir": "dir"},
			}},
			pathToRemove: filepath.Join("link_to_dir", "file.txt"),
		},
		{
			name: "Remove broken symlink",
			setup: matchesRealSetup{unittestSetup{
				initialSymlinks: map[string]string{"broken_link": "nonexistent"},
			}},
			pathToRemove: "broken_link",
		},
		{
			name: "Remove symlink loop",
			setup: matchesRealSetup{unittestSetup{
				initialSymlinks: map[string]string{
					"loop1": "loop2",
					"loop2": "loop1",
				},
			}},
			pathToRemove: "loop1",
		},
		{
			name: "Error removing path with symlink loop in parent",
			setup: matchesRealSetup{unittestSetup{
				initialSymlinks: map[string]string{
					"loop1": "loop2",
					"loop2": "loop1",
				},
			}},
			pathToRemove: filepath.Join("loop1", "file.txt"),
		},
		{
			name: "Error removing path with broken symlink in parent",
			setup: matchesRealSetup{unittestSetup{
				initialSymlinks: map[string]string{"broken_link": "nonexistent"},
			}},
			pathToRemove: filepath.Join("broken_link", "file.txt"),
		},
	}

	for _, tc := range tests {
		t.Run(tc.name, func(t *testing.T) {
			realRoot, realFS, testFS := tc.setup.setup(t)
			defer os.RemoveAll(realRoot)

			// Execute
			realErr := realFS.Remove(filepath.Join(realRoot, tc.pathToRemove))
			testErr := testFS.Remove(tc.pathToRemove)

			requireErrorsMatch(t, realErr, testErr)
			if realErr == nil {
				requireFileSystemsMatch(t, realRoot, testFS)
			}
		})
	}
}