#![cfg(test)]

use std::{
    fs,
    os::unix::fs::symlink,
    path::{Path, PathBuf},
    process::{Command, Output},
};

use tempfile::{TempDir, tempdir};

struct Fixture {
    dir: TempDir,
    config: PathBuf,
}

impl Fixture {
    fn new(script: &str) -> Self {
        let dir = tempdir().unwrap();
        // Only the child process sees this PATH. The real zfs cannot be found.
        symlink(
            Path::new(env!("CARGO_MANIFEST_DIR")).join("tests/fixtures/zfs"),
            dir.path().join("zfs"),
        )
        .unwrap();
        // The executable is a checked-in fixture; scenario files are read by
        // its shell, so parallel tests never execute a file being written.
        fs::write(dir.path().join("scenario"), script).unwrap();
        let config = dir.path().join("config.toml");
        fs::write(
            &config,
            "[default]\n15_min = 1\nhourly = 0\ndaily = 0\nmonthly = 0\n",
        )
        .unwrap();
        Self { dir, config }
    }

    fn calls(&self) -> Vec<String> {
        fs::read_to_string(self.dir.path().join("calls"))
            .unwrap_or_default()
            .lines()
            .map(String::from)
            .collect()
    }

    fn normalized_calls(&self) -> Vec<String> {
        self.calls()
            .into_iter()
            .map(|call| {
                if call.starts_with("snapshot ") {
                    let (dataset, name) = call.split_once('@').unwrap();
                    assert!(name.starts_with("auto_"), "{call}");
                    format!("{dataset}@<timestamp>")
                } else {
                    call
                }
            })
            .collect()
    }

    fn run(&self) -> Output {
        Command::new(env!("CARGO_BIN_EXE_snapshot-manager"))
            .current_dir(self.dir.path())
            .env("PATH", self.dir.path())
            .env("SNAPSHOT_TEST_SCRIPT", self.dir.path().join("scenario"))
            .env_remove("SIGNAL_ALERTS")
            .env_remove("SIGNAL_ALERT_FROM_PHONE")
            .env_remove("SIGNAL_ALERT_TO_PHONE")
            .env_remove("RUST_LOG")
            .arg(&self.config)
            .output()
            .unwrap()
    }
}

fn stderr(output: &Output) -> &str {
    std::str::from_utf8(&output.stderr).unwrap()
}

#[test]
fn creates_then_prunes_only_this_datasets_managed_snapshots() {
    let fixture = Fixture::new(
        r#"
case "$*" in
  'list -Hp -t filesystem -o name')
    printf '%s\n' pool pool/home
    printf '%s\n' 'warning on stderr' >&2 ;;
  'snapshot pool/home@auto_'*) ;;
  'list -Hp -t snapshot -o name -d 1 pool/home')
    printf '%s\n' pool/home@auto_200002020145 pool/home@auto_200002020115 pool/home@manual pool/home@manual_auto_200001010015 pool/home/child@auto_200001010015 pool/other@auto_200001010015 ;;
  'destroy pool/home@auto_200002020115') ;;
  *) exit 99 ;;
esac
"#,
    );
    let output = fixture.run();
    assert!(output.status.success(), "{}", stderr(&output));
    assert_eq!(
        fixture.normalized_calls(),
        [
            "list -Hp -t filesystem -o name",
            "snapshot pool/home@<timestamp>",
            "list -Hp -t snapshot -o name -d 1 pool/home",
            "destroy pool/home@auto_200002020115",
        ]
    );
}

#[test]
fn failed_or_duplicate_creation_skips_pruning_but_continues() {
    for error in ["snapshot already exists", "permission denied"] {
        let fixture = Fixture::new(&format!(
            r#"
case "$*" in
  'list -Hp -t filesystem -o name') printf '%s\n' pool/home pool/other ;;
  'snapshot pool/home@auto_'*) printf '%s\n' '{error}' >&2; exit 1 ;;
  'snapshot pool/other@auto_'*) ;;
  'list -Hp -t snapshot -o name -d 1 pool/other') ;;
  *) exit 99 ;;
esac
"#
        ));
        let output = fixture.run();
        assert!(output.status.success(), "{}", stderr(&output));
        assert!(stderr(&output).contains("pool/home failed to create snapshot auto_"));
        assert!(stderr(&output).contains(error));
        assert_eq!(
            fixture.normalized_calls(),
            [
                "list -Hp -t filesystem -o name",
                "snapshot pool/home@<timestamp>",
                "snapshot pool/other@<timestamp>",
                "list -Hp -t snapshot -o name -d 1 pool/other",
            ]
        );
        let calls = fixture.calls();
        assert_eq!(
            calls[1].split_once('@').unwrap().1,
            calls[2].split_once('@').unwrap().1
        );
    }
}

#[test]
fn dependent_clone_failure_is_reported_and_remaining_deletions_continue() {
    let fixture = Fixture::new(
        r#"
case "$*" in
  'list -Hp -t filesystem -o name') printf '%s\n' pool/home ;;
  'snapshot pool/home@auto_'*) ;;
  'list -Hp -t snapshot -o name -d 1 pool/home')
    printf '%s\n' pool/home@auto_200002020115 pool/home@auto_200002020130 pool/home@auto_200002020145 ;;
  'destroy pool/home@auto_200002020115')
    printf '%s\n' "cannot destroy 'pool/home@auto_200002020115': snapshot has dependent clones" >&2; exit 1 ;;
  'destroy pool/home@auto_200002020130') ;;
  *) exit 99 ;;
esac
"#,
    );
    let output = fixture.run();
    assert!(output.status.success(), "{}", stderr(&output));
    assert!(
        stderr(&output).contains(
            "pool/home@auto_200002020115 failed to delete: snapshot has dependent clones"
        )
    );
    assert_eq!(
        fixture.calls().last().unwrap(),
        "destroy pool/home@auto_200002020130"
    );
}

#[test]
fn unexpected_destroy_failure_aborts_and_reports_the_error() {
    let fixture = Fixture::new(
        r#"
case "$1" in
  list)
    if [ "$4" = filesystem ]; then
      printf '%s\n' pool/home
    else
      printf '%s\n' pool/home@auto_200002020115 pool/home@auto_200002020130 pool/home@auto_200002020145
    fi ;;
  snapshot) ;;
  destroy) printf '%s\n' 'permission denied' >&2; exit 1 ;;
esac
"#,
    );
    let output = fixture.run();
    assert_eq!(output.status.code(), Some(1), "{}", stderr(&output));
    assert!(stderr(&output).contains("permission denied"));
    assert!(stderr(&output).contains("snapshot_manager failed"));
    assert_eq!(
        fixture.calls().last().unwrap(),
        "destroy pool/home@auto_200002020115"
    );
}

#[test]
fn failed_list_never_uses_partial_output() {
    for stream in ["", " >&2"] {
        let fixture = Fixture::new(&format!(
            "printf '%s\\n' pool/home\nprintf '%s\\n' 'cannot list datasets'{stream}\nexit 1"
        ));
        let output = fixture.run();
        assert_eq!(output.status.code(), Some(1), "{}", stderr(&output));
        assert!(stderr(&output).contains("cannot list datasets"));
        assert!(stderr(&output).contains("snapshot_manager failed"));
        assert_eq!(fixture.calls(), ["list -Hp -t filesystem -o name"]);
    }
}

#[test]
fn failed_snapshot_listing_aborts_without_destroying_anything() {
    let fixture = Fixture::new(
        r#"
case "$*" in
  'list -Hp -t filesystem -o name') printf '%s\n' pool/home ;;
  'snapshot pool/home@auto_'*) ;;
  *) printf '%s\n' pool/home@auto_200002020115; exit 1 ;;
esac
"#,
    );
    let output = fixture.run();
    assert_eq!(output.status.code(), Some(1), "{}", stderr(&output));
    assert!(stderr(&output).contains("snapshot_manager failed"));
    assert_eq!(fixture.calls().len(), 3);
}

#[test]
fn invalid_config_stops_before_any_zfs_commands() {
    let fixture = Fixture::new("exit 99");
    fs::write(
        &fixture.config,
        "[default]\n15_min = -1\nhourly = 1\ndaily = 0\nmonthly = 0",
    )
    .unwrap();
    let output = fixture.run();
    assert_eq!(output.status.code(), Some(1), "{}", stderr(&output));
    assert!(stderr(&output).contains("Invalid configuration"));
    assert!(fixture.calls().is_empty());
}

#[test]
fn missing_zfs_executable_fails_and_reports_the_error() {
    let fixture = Fixture::new("exit 99");
    fs::remove_file(fixture.dir.path().join("zfs")).unwrap();
    let output = fixture.run();
    assert_eq!(output.status.code(), Some(1), "{}", stderr(&output));
    assert!(stderr(&output).contains("Failed to execute zfs"));
    assert!(stderr(&output).contains("snapshot_manager failed"));
    assert!(fixture.calls().is_empty());
}

#[test]
fn dataset_names_are_passed_as_one_argument_without_a_shell() {
    let fixture = Fixture::new(
        r#"
case "$1" in
  list)
    [ "$*" = 'list -Hp -t filesystem -o name' ] || exit 98
    printf '%s\n' 'pool/two words;touch injected' ;;
  snapshot)
    [ "$#" -eq 2 ] || exit 97
    case "$2" in
      'pool/two words;touch injected@auto_'*) printf '%s\n' 'argument preserved' >&2; exit 1 ;;
      *) exit 96 ;;
    esac ;;
  *) exit 99 ;;
esac
"#,
    );
    let output = fixture.run();
    assert!(output.status.success(), "{}", stderr(&output));
    assert!(stderr(&output).contains("argument preserved"));
    assert_eq!(
        fixture.normalized_calls(),
        [
            "list -Hp -t filesystem -o name",
            "snapshot pool/two words;touch injected@<timestamp>"
        ]
    );
    assert!(fs::read_dir(fixture.dir.path()).unwrap().all(|entry| {
        !entry
            .unwrap()
            .file_name()
            .to_string_lossy()
            .starts_with("injected")
    }));
}