package daemon

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

	"banger/internal/paths"
)

// TestSameDirOrParentHandlesSymlinks guards against a drift where
// sameDirOrParent (the gate that protects a user key under the
// legacy dir from the cleanup scrub) compares lexical paths and
// misses symlink aliasing.
//
// Scenario: user configured ssh_key_path at a path that lands inside
// ConfigDir/ssh via a symlink (e.g. ConfigDir is itself symlinked,
// or the user maintains a symlink alias for their key tree). The
// gate must resolve both sides to the same physical location and
// refuse to scrub.
func TestSameDirOrParentHandlesSymlinks(t *testing.T) {
	physical := t.TempDir()
	realDir := filepath.Join(physical, "real-ssh")
	if err := os.Mkdir(realDir, 0o700); err != nil {
		t.Fatalf("Mkdir: %v", err)
	}
	realKey := filepath.Join(realDir, "id_ed25519")
	if err := os.WriteFile(realKey, []byte("PRIVATE"), 0o600); err != nil {
		t.Fatalf("WriteFile: %v", err)
	}

	// A symlink that aliases the whole real-ssh directory. The user
	// configured ssh_key_path via this alias, but sameDirOrParent is
	// called with the canonical (realDir) legacyDir path.
	aliasDir := filepath.Join(physical, "alias-ssh")
	if err := os.Symlink(realDir, aliasDir); err != nil {
		t.Skipf("symlink unsupported on this filesystem: %v", err)
	}
	aliasKey := filepath.Join(aliasDir, "id_ed25519")

	if !sameDirOrParent(realDir, aliasKey) {
		t.Fatalf("sameDirOrParent(%q, %q) = false; symlinked key was not recognised as inside the dir — cleanup would delete it", realDir, aliasKey)
	}

	// Reverse direction: dir provided as a symlink, key as canonical.
	if !sameDirOrParent(aliasDir, realKey) {
		t.Fatalf("sameDirOrParent(%q, %q) = false; reverse symlink direction also missed", aliasDir, realKey)
	}

	// Negative: a key in a completely unrelated directory must not
	// be reported inside either spelling of the legacy dir.
	outside := filepath.Join(t.TempDir(), "other", "id_ed25519")
	if err := os.MkdirAll(filepath.Dir(outside), 0o700); err != nil {
		t.Fatalf("MkdirAll: %v", err)
	}
	if err := os.WriteFile(outside, []byte("UNRELATED"), 0o600); err != nil {
		t.Fatalf("WriteFile: %v", err)
	}
	if sameDirOrParent(realDir, outside) {
		t.Fatalf("sameDirOrParent(%q, %q) = true; unrelated dir incorrectly flagged as inside", realDir, outside)
	}
}

// A user-configured ssh_key_path that happens to live under the
// legacy $ConfigDir/ssh directory must survive the pre-opt-in
// migration cleanup. The old code did os.RemoveAll on the whole
// directory, which nuked the key. Pin the narrower behavior so a
// future refactor can't re-broaden the scrub.
func TestSyncVMSSHClientConfigPreservesUserKeyInLegacyDir(t *testing.T) {
	homeDir := t.TempDir()
	t.Setenv("HOME", homeDir)

	configDir := filepath.Join(homeDir, ".config", "banger")
	legacyDir := filepath.Join(configDir, "ssh")
	if err := os.MkdirAll(legacyDir, 0o700); err != nil {
		t.Fatalf("MkdirAll: %v", err)
	}
	userKey := filepath.Join(legacyDir, "id_ed25519")
	if err := os.WriteFile(userKey, []byte("PRIVATE"), 0o600); err != nil {
		t.Fatalf("WriteFile: %v", err)
	}
	// A stale ssh_config under the same dir from pre-opt-in era.
	legacyConfig := filepath.Join(legacyDir, "ssh_config")
	if err := os.WriteFile(legacyConfig, []byte("stale"), 0o644); err != nil {
		t.Fatalf("WriteFile: %v", err)
	}

	layout := paths.Layout{
		ConfigDir:      configDir,
		KnownHostsPath: filepath.Join(homeDir, ".local", "state", "banger", "ssh", "known_hosts"),
	}
	if err := syncVMSSHClientConfig(layout, userKey); err != nil {
		t.Fatalf("syncVMSSHClientConfig: %v", err)
	}

	// The configured key must survive.
	if _, err := os.Stat(userKey); err != nil {
		t.Fatalf("user-configured key disappeared: %v", err)
	}
	// Enclosing directory must also survive (it contains the key).
	if _, err := os.Stat(legacyDir); err != nil {
		t.Fatalf("legacy dir removed despite containing the configured key: %v", err)
	}
	// The stale legacy ssh_config file can still be gone in this
	// case — the user's key isn't ssh_config, so cleaning up the
	// sibling file is fine. We don't assert either way, since the
	// gate is "don't delete the user's key" not "always delete the
	// sibling file."
}

// With ssh_key_path configured outside ConfigDir/ssh, the legacy
// migration step should scrub the old sibling file and then the
// (now-empty) directory — no os.RemoveAll on anything still in use.
func TestSyncVMSSHClientConfigNarrowsCleanupToLegacyFile(t *testing.T) {
	homeDir := t.TempDir()
	t.Setenv("HOME", homeDir)

	configDir := filepath.Join(homeDir, ".config", "banger")
	legacyDir := filepath.Join(configDir, "ssh")
	if err := os.MkdirAll(legacyDir, 0o700); err != nil {
		t.Fatalf("MkdirAll: %v", err)
	}
	// Simulate the pre-opt-in leftover: just the ssh_config file.
	legacyConfig := filepath.Join(legacyDir, "ssh_config")
	if err := os.WriteFile(legacyConfig, []byte("stale"), 0o644); err != nil {
		t.Fatalf("WriteFile: %v", err)
	}

	// ssh_key_path lives in the state dir (the new default location).
	stateDir := filepath.Join(homeDir, ".local", "state", "banger", "ssh")
	if err := os.MkdirAll(stateDir, 0o700); err != nil {
		t.Fatalf("MkdirAll: %v", err)
	}
	userKey := filepath.Join(stateDir, "id_ed25519")
	if err := os.WriteFile(userKey, []byte("PRIVATE"), 0o600); err != nil {
		t.Fatalf("WriteFile: %v", err)
	}

	layout := paths.Layout{
		ConfigDir:      configDir,
		KnownHostsPath: filepath.Join(homeDir, ".local", "state", "banger", "ssh", "known_hosts"),
	}
	if err := syncVMSSHClientConfig(layout, userKey); err != nil {
		t.Fatalf("syncVMSSHClientConfig: %v", err)
	}

	// Legacy ssh_config file: gone.
	if _, err := os.Stat(legacyConfig); !os.IsNotExist(err) {
		t.Fatalf("legacy ssh_config survived cleanup: %v", err)
	}
	// Legacy dir: gone, since it was empty after the file removal.
	if _, err := os.Stat(legacyDir); !os.IsNotExist(err) {
		t.Fatalf("legacy dir survived cleanup when empty: %v", err)
	}
	// User's key: untouched.
	if _, err := os.Stat(userKey); err != nil {
		t.Fatalf("user key disappeared: %v", err)
	}
}

// If the legacy dir contains UNEXPECTED files (not ssh_config, not
// the configured key), leave the dir alone. os.Remove on a non-
// empty dir errors with ENOTEMPTY, which we swallow. Regression
// guard so the cleanup can never escalate to recursive deletion.
func TestSyncVMSSHClientConfigLeavesUnexpectedLegacyContents(t *testing.T) {
	homeDir := t.TempDir()
	t.Setenv("HOME", homeDir)

	configDir := filepath.Join(homeDir, ".config", "banger")
	legacyDir := filepath.Join(configDir, "ssh")
	if err := os.MkdirAll(legacyDir, 0o700); err != nil {
		t.Fatalf("MkdirAll: %v", err)
	}
	// A user-managed file we have no business removing.
	userFile := filepath.Join(legacyDir, "my-other-thing")
	if err := os.WriteFile(userFile, []byte("mine"), 0o600); err != nil {
		t.Fatalf("WriteFile: %v", err)
	}

	layout := paths.Layout{
		ConfigDir:      configDir,
		KnownHostsPath: filepath.Join(homeDir, ".local", "state", "banger", "ssh", "known_hosts"),
	}
	// ssh_key_path lives elsewhere; cleanup would otherwise proceed.
	stateKey := filepath.Join(homeDir, ".local", "state", "banger", "ssh", "id_ed25519")
	if err := os.MkdirAll(filepath.Dir(stateKey), 0o700); err != nil {
		t.Fatalf("MkdirAll: %v", err)
	}
	if err := os.WriteFile(stateKey, []byte("PRIVATE"), 0o600); err != nil {
		t.Fatalf("WriteFile: %v", err)
	}

	if err := syncVMSSHClientConfig(layout, stateKey); err != nil {
		t.Fatalf("syncVMSSHClientConfig: %v", err)
	}

	if _, err := os.Stat(userFile); err != nil {
		t.Fatalf("user-managed legacy-dir file disappeared: %v", err)
	}
	if _, err := os.Stat(legacyDir); err != nil {
		t.Fatalf("legacy dir vanished despite non-empty contents: %v", err)
	}
}

// Under the opt-in contract the daemon writes its own ssh_config file
// and never touches ~/.ssh/config on its own.
func TestSyncVMSSHClientConfigWritesBangerFileOnly(t *testing.T) {
	homeDir := t.TempDir()
	t.Setenv("HOME", homeDir)

	knownHostsPath := filepath.Join(homeDir, ".local", "state", "banger", "ssh", "known_hosts")
	layout := paths.Layout{
		ConfigDir:      filepath.Join(homeDir, ".config", "banger"),
		KnownHostsPath: knownHostsPath,
	}
	keyPath := filepath.Join(homeDir, ".config", "banger", "ssh", "id_ed25519")

	if err := syncVMSSHClientConfig(layout, keyPath); err != nil {
		t.Fatalf("syncVMSSHClientConfig: %v", err)
	}

	// Banger's own ssh_config file has the `Host *.vm` stanza.
	bangerConfig, err := os.ReadFile(BangerSSHConfigPath(layout))
	if err != nil {
		t.Fatalf("ReadFile(banger ssh_config): %v", err)
	}
	for _, want := range []string{
		"Host *.vm",
		"IdentityFile " + keyPath,
		"UserKnownHostsFile " + knownHostsPath,
		"StrictHostKeyChecking accept-new",
	} {
		if !strings.Contains(string(bangerConfig), want) {
			t.Fatalf("banger ssh_config missing %q:\n%s", want, bangerConfig)
		}
	}

	// ~/.ssh/config must NOT have been created or modified.
	if _, err := os.Stat(filepath.Join(homeDir, ".ssh", "config")); !os.IsNotExist(err) {
		t.Fatalf("~/.ssh/config should be untouched; stat err = %v", err)
	}

	// Regression: the legacy posture (strict no + /dev/null) must not
	// reappear in the banger file.
	for _, must := range []string{
		"StrictHostKeyChecking no",
		"UserKnownHostsFile /dev/null",
	} {
		if strings.Contains(string(bangerConfig), must) {
			t.Fatalf("banger ssh_config leaked legacy posture %q:\n%s", must, bangerConfig)
		}
	}
}

func TestInstallUserSSHIncludeAddsIncludeBlock(t *testing.T) {
	homeDir := t.TempDir()
	t.Setenv("HOME", homeDir)

	layout := paths.Layout{ConfigDir: filepath.Join(homeDir, ".config", "banger")}
	if err := os.MkdirAll(layout.ConfigDir, 0o755); err != nil {
		t.Fatalf("MkdirAll: %v", err)
	}
	// Write a fake banger ssh_config so Install has something to include.
	if err := os.WriteFile(BangerSSHConfigPath(layout), []byte("Host *.vm\n"), 0o644); err != nil {
		t.Fatalf("WriteFile(banger ssh_config): %v", err)
	}

	if err := InstallUserSSHInclude(layout); err != nil {
		t.Fatalf("InstallUserSSHInclude: %v", err)
	}
	got, err := os.ReadFile(filepath.Join(homeDir, ".ssh", "config"))
	if err != nil {
		t.Fatalf("ReadFile(~/.ssh/config): %v", err)
	}
	want := "Include " + BangerSSHConfigPath(layout)
	if !strings.Contains(string(got), want) {
		t.Fatalf("user config missing %q:\n%s", want, got)
	}
	if !strings.Contains(string(got), bangerSSHIncludeBegin) {
		t.Fatalf("user config missing begin marker:\n%s", got)
	}
}

func TestInstallUserSSHIncludeIsIdempotent(t *testing.T) {
	homeDir := t.TempDir()
	t.Setenv("HOME", homeDir)

	layout := paths.Layout{ConfigDir: filepath.Join(homeDir, ".config", "banger")}
	if err := os.MkdirAll(layout.ConfigDir, 0o755); err != nil {
		t.Fatalf("MkdirAll: %v", err)
	}
	if err := os.WriteFile(BangerSSHConfigPath(layout), []byte("Host *.vm\n"), 0o644); err != nil {
		t.Fatalf("WriteFile: %v", err)
	}
	for i := 0; i < 3; i++ {
		if err := InstallUserSSHInclude(layout); err != nil {
			t.Fatalf("InstallUserSSHInclude (%d): %v", i, err)
		}
	}
	got, err := os.ReadFile(filepath.Join(homeDir, ".ssh", "config"))
	if err != nil {
		t.Fatalf("ReadFile: %v", err)
	}
	if n := strings.Count(string(got), bangerSSHIncludeBegin); n != 1 {
		t.Fatalf("begin markers = %d, want 1:\n%s", n, got)
	}
}

func TestInstallUserSSHIncludeMigratesLegacyInlineBlock(t *testing.T) {
	homeDir := t.TempDir()
	t.Setenv("HOME", homeDir)

	layout := paths.Layout{ConfigDir: filepath.Join(homeDir, ".config", "banger")}
	if err := os.MkdirAll(layout.ConfigDir, 0o755); err != nil {
		t.Fatalf("MkdirAll: %v", err)
	}
	if err := os.WriteFile(BangerSSHConfigPath(layout), []byte("Host *.vm\n"), 0o644); err != nil {
		t.Fatalf("WriteFile: %v", err)
	}

	sshDir := filepath.Join(homeDir, ".ssh")
	if err := os.MkdirAll(sshDir, 0o700); err != nil {
		t.Fatalf("MkdirAll(.ssh): %v", err)
	}
	legacy := strings.Join([]string{
		"ServerAliveInterval 120",
		"",
		vmSSHConfigIncludeBegin,
		"Host *.vm",
		"    User root",
		"    IdentityFile /some/old/key",
		vmSSHConfigIncludeEnd,
		"",
		"Host other",
		"    HostName 192.0.2.5",
		"",
	}, "\n")
	if err := os.WriteFile(filepath.Join(sshDir, "config"), []byte(legacy), 0o600); err != nil {
		t.Fatalf("seed legacy config: %v", err)
	}

	if err := InstallUserSSHInclude(layout); err != nil {
		t.Fatalf("InstallUserSSHInclude: %v", err)
	}
	got, err := os.ReadFile(filepath.Join(sshDir, "config"))
	if err != nil {
		t.Fatalf("ReadFile: %v", err)
	}
	gotStr := string(got)
	// Legacy inline block must be gone.
	if strings.Contains(gotStr, vmSSHConfigIncludeBegin) {
		t.Fatalf("legacy inline block survived:\n%s", gotStr)
	}
	// New Include block must be present.
	if !strings.Contains(gotStr, bangerSSHIncludeBegin) {
		t.Fatalf("new include block missing:\n%s", gotStr)
	}
	// Unrelated stanzas must be preserved.
	for _, want := range []string{"ServerAliveInterval 120", "Host other"} {
		if !strings.Contains(gotStr, want) {
			t.Fatalf("user config lost unrelated entry %q:\n%s", want, gotStr)
		}
	}
}

func TestUninstallUserSSHIncludeRemovesBothMarkerBlocks(t *testing.T) {
	homeDir := t.TempDir()
	t.Setenv("HOME", homeDir)

	sshDir := filepath.Join(homeDir, ".ssh")
	if err := os.MkdirAll(sshDir, 0o700); err != nil {
		t.Fatalf("MkdirAll: %v", err)
	}
	seed := strings.Join([]string{
		"Host keep",
		"    HostName 198.51.100.1",
		"",
		vmSSHConfigIncludeBegin,
		"Host *.vm",
		vmSSHConfigIncludeEnd,
		"",
		bangerSSHIncludeBegin,
		"Include /tmp/banger-ssh-config",
		bangerSSHIncludeEnd,
		"",
	}, "\n")
	if err := os.WriteFile(filepath.Join(sshDir, "config"), []byte(seed), 0o600); err != nil {
		t.Fatalf("seed: %v", err)
	}

	if err := UninstallUserSSHInclude(); err != nil {
		t.Fatalf("UninstallUserSSHInclude: %v", err)
	}
	got, err := os.ReadFile(filepath.Join(sshDir, "config"))
	if err != nil {
		t.Fatalf("ReadFile: %v", err)
	}
	gotStr := string(got)
	for _, banned := range []string{vmSSHConfigIncludeBegin, bangerSSHIncludeBegin} {
		if strings.Contains(gotStr, banned) {
			t.Fatalf("residue of %q:\n%s", banned, gotStr)
		}
	}
	if !strings.Contains(gotStr, "Host keep") {
		t.Fatalf("lost unrelated entry:\n%s", gotStr)
	}
}

func TestUninstallUserSSHIncludeIsNoOpWhenMissing(t *testing.T) {
	homeDir := t.TempDir()
	t.Setenv("HOME", homeDir)
	if err := UninstallUserSSHInclude(); err != nil {
		t.Fatalf("UninstallUserSSHInclude on missing file: %v", err)
	}
	// Still no ~/.ssh/config.
	if _, err := os.Stat(filepath.Join(homeDir, ".ssh", "config")); !os.IsNotExist(err) {
		t.Fatalf("~/.ssh/config unexpectedly created; stat err = %v", err)
	}
}

func TestUserSSHIncludeInstalledDetectsBothMarkers(t *testing.T) {
	for _, tc := range []struct {
		name   string
		seed   string
		wantIn bool
	}{
		{"missing file", "", false},
		{"unrelated only", "Host other\n    HostName 1.2.3.4\n", false},
		{"legacy marker", vmSSHConfigIncludeBegin + "\nHost *.vm\n" + vmSSHConfigIncludeEnd + "\n", true},
		{"new marker", bangerSSHIncludeBegin + "\nInclude /tmp/banger\n" + bangerSSHIncludeEnd + "\n", true},
	} {
		t.Run(tc.name, func(t *testing.T) {
			homeDir := t.TempDir()
			t.Setenv("HOME", homeDir)
			if tc.seed != "" {
				if err := os.MkdirAll(filepath.Join(homeDir, ".ssh"), 0o700); err != nil {
					t.Fatalf("MkdirAll: %v", err)
				}
				if err := os.WriteFile(filepath.Join(homeDir, ".ssh", "config"), []byte(tc.seed), 0o600); err != nil {
					t.Fatalf("WriteFile: %v", err)
				}
			}
			got, err := UserSSHIncludeInstalled()
			if err != nil {
				t.Fatalf("UserSSHIncludeInstalled: %v", err)
			}
			if got != tc.wantIn {
				t.Fatalf("got %v, want %v", got, tc.wantIn)
			}
		})
	}
}