use std::fs;
use std::path::{Path, PathBuf};
use std::sync::atomic::{AtomicUsize, Ordering};

use nix_style_linter::RunStatus;

static TEST_DIRECTORY_ID: AtomicUsize = AtomicUsize::new(0);

#[test]
fn malformed_file_reports_parse_error() {
    let workspace = TestWorkspace::new("malformed_file_reports_parse_error");
    let path = workspace.write("broken.nix", "let x = ; in x\n");

    let output = run_linter(&[path]);

    assert_eq!(output.status, RunStatus::Diagnostics);
    assert_eq!(output.stderr, "");
    assert!(output.stdout.starts_with(&format!(
        "{}:1:9: parse-error: unexpected TOKEN_SEMICOLON at 8..9",
        workspace.path("broken.nix").display()
    )));
    assert!(!output.stdout.contains("let-order"));
}

#[test]
fn forward_reference_reports_let_order() {
    let workspace = TestWorkspace::new("forward_reference_reports_let_order");
    let path = workspace.write(
        "forward.nix",
        "let\n  app = package;\n  package = \"hello\";\nin app\n",
    );

    let output = run_linter(&[path]);

    assert_eq!(output.status, RunStatus::Diagnostics);
    assert_eq!(output.stderr, "");
    assert_eq!(
        output.stdout,
        format!(
            "{}:2:3: let-order: `app` references later let binding `package`\n",
            workspace.path("forward.nix").display()
        )
    );
}

#[test]
fn dependency_ordered_bindings_exit_clean() {
    let workspace = TestWorkspace::new("dependency_ordered_bindings_exit_clean");
    let path = workspace.write(
        "ordered.nix",
        "let\n  package = \"hello\";\n  app = package;\nin app\n",
    );

    let output = run_linter(&[path]);

    assert_eq!(output.status, RunStatus::Clean);
    assert_eq!(output.stdout, "");
    assert_eq!(output.stderr, "");
}

#[test]
fn outer_scope_reference_exits_clean() {
    let workspace = TestWorkspace::new("outer_scope_reference_exits_clean");
    let path = workspace.write(
        "outer.nix",
        "let\n  package = \"hello\";\nin\nlet\n  app = package;\nin app\n",
    );

    let output = run_linter(&[path]);

    assert_eq!(output.status, RunStatus::Clean);
    assert_eq!(output.stdout, "");
    assert_eq!(output.stderr, "");
}

#[test]
fn nested_lambda_parameter_shadows_later_binding() {
    let workspace = TestWorkspace::new("nested_lambda_parameter_shadows_later_binding");
    let path = workspace.write(
        "lambda.nix",
        "let\n  call = package: package;\n  package = \"hello\";\nin call\n",
    );

    let output = run_linter(&[path]);

    assert_eq!(output.status, RunStatus::Clean);
    assert_eq!(output.stdout, "");
    assert_eq!(output.stderr, "");
}

#[test]
fn nested_let_binding_shadows_later_binding() {
    let workspace = TestWorkspace::new("nested_let_binding_shadows_later_binding");
    let path = workspace.write(
        "nested-let.nix",
        "let\n  app = let package = \"inner\"; in package;\n  package = \"outer\";\nin app\n",
    );

    let output = run_linter(&[path]);

    assert_eq!(output.status, RunStatus::Clean);
    assert_eq!(output.stdout, "");
    assert_eq!(output.stderr, "");
}

#[test]
fn earlier_sibling_constant_shared_by_multiple_bindings_exits_clean() {
    let workspace = TestWorkspace::new("earlier_sibling_constant_shared_by_multiple_bindings");
    let path = workspace.write(
        "shared.nix",
        "let\n  package = \"hello\";\n  app = package;\n  shell = package;\nin [ app shell ]\n",
    );

    let output = run_linter(&[path]);

    assert_eq!(output.status, RunStatus::Clean);
    assert_eq!(output.stdout, "");
    assert_eq!(output.stderr, "");
}

#[test]
fn previous_line_suppression_disables_let_order() {
    let workspace = TestWorkspace::new("previous_line_suppression_disables_let_order");
    let path = workspace.write(
        "suppressed.nix",
        "let\n  # nix-style-linter: disable-next-line let-order -- intentional recursion\n  app = package;\n  package = app;\nin app\n",
    );

    let output = run_linter(&[path]);

    assert_eq!(output.status, RunStatus::Clean);
    assert_eq!(output.stdout, "");
    assert_eq!(output.stderr, "");
}

#[test]
fn malformed_suppression_does_not_disable_let_order() {
    let workspace = TestWorkspace::new("malformed_suppression_does_not_disable_let_order");
    let path = workspace.write(
        "unsuppressed.nix",
        "let\n  # nix-style-linter: disable-next-line let-order\n  app = package;\n  package = \"hello\";\nin app\n",
    );

    let output = run_linter(&[path]);

    assert_eq!(output.status, RunStatus::Diagnostics);
    assert_eq!(
        output.stdout,
        format!(
            "{}:3:3: let-order: `app` references later let binding `package`\n",
            workspace.path("unsuppressed.nix").display()
        )
    );
    assert_eq!(output.stderr, "");
}

#[test]
fn unsupported_binding_syntax_is_skipped() {
    let workspace = TestWorkspace::new("unsupported_binding_syntax_is_skipped");
    let path = workspace.write(
        "unsupported.nix",
        "let\n  attrs.value = package;\n  inherit package;\n  package = \"hello\";\nin attrs\n",
    );

    let output = run_linter(&[path]);

    assert_eq!(output.status, RunStatus::Clean);
    assert_eq!(output.stdout, "");
    assert_eq!(output.stderr, "");
}

#[test]
fn valid_file_exits_clean() {
    let workspace = TestWorkspace::new("valid_file_exits_clean");
    let path = workspace.write("valid.nix", "let x = 1; in x\n");

    let output = run_linter(&[path]);

    assert_eq!(output.status, RunStatus::Clean);
    assert_eq!(output.stdout, "");
    assert_eq!(output.stderr, "");
}

#[test]
fn missing_path_reports_tool_error() {
    let workspace = TestWorkspace::new("missing_path_reports_tool_error");
    let path = workspace.path("missing.nix");

    let output = run_linter(&[path.clone()]);

    assert_eq!(output.status, RunStatus::ToolError);
    assert_eq!(output.stdout, "");
    assert!(output.stderr.starts_with(&format!(
        "error: failed to inspect {}:",
        path.display()
    )));
}

#[test]
fn directory_inputs_recurse_through_nix_files() {
    let workspace = TestWorkspace::new("directory_inputs_recurse_through_nix_files");
    workspace.write("ignored.txt", "let x = ; in x\n");
    workspace.write("nested/broken.nix", "let\n  x = 1;\n  y = ;\nin y\n");

    let output = run_linter(&[workspace.root.clone()]);

    assert_eq!(output.status, RunStatus::Diagnostics);
    assert_eq!(output.stderr, "");
    assert!(output.stdout.starts_with(&format!(
        "{}:3:7: parse-error: unexpected TOKEN_SEMICOLON at 19..20",
        workspace.path("nested/broken.nix").display()
    )));
    assert!(!output.stdout.contains("ignored.txt"));
}

#[test]
fn empty_invocation_reports_tool_error() {
    let output = run_linter(&[]);

    assert_eq!(output.status, RunStatus::ToolError);
    assert_eq!(output.stdout, "");
    assert_eq!(output.stderr, "error: expected at least one path\n");
}

struct LinterOutput {
    status: RunStatus,
    stdout: String,
    stderr: String,
}

fn run_linter(paths: &[PathBuf]) -> LinterOutput {
    let mut stdout = Vec::new();
    let mut stderr = Vec::new();
    let status = nix_style_linter::run(paths, &mut stdout, &mut stderr).unwrap();

    LinterOutput {
        status,
        stdout: String::from_utf8(stdout).unwrap(),
        stderr: String::from_utf8(stderr).unwrap(),
    }
}

struct TestWorkspace {
    root: PathBuf,
}

impl TestWorkspace {
    fn new(name: &str) -> Self {
        let id = TEST_DIRECTORY_ID.fetch_add(1, Ordering::Relaxed);
        let root = std::env::temp_dir().join(format!(
            "nix-style-linter-{process}-{name}-{id}",
            process = std::process::id()
        ));

        if root.exists() {
            fs::remove_dir_all(&root).unwrap();
        }
        fs::create_dir_all(&root).unwrap();

        Self { root }
    }

    fn path(&self, relative: impl AsRef<Path>) -> PathBuf {
        self.root.join(relative)
    }

    fn write(&self, relative: impl AsRef<Path>, contents: &str) -> PathBuf {
        let path = self.path(relative);
        if let Some(parent) = path.parent() {
            fs::create_dir_all(parent).unwrap();
        }
        fs::write(&path, contents).unwrap();
        path
    }
}

impl Drop for TestWorkspace {
    fn drop(&mut self) {
        fs::remove_dir_all(&self.root).unwrap();
    }
}