//! Test commands for running various test suites.
//!
//! This module provides commands for running different types of tests:
//!
//! - **Unit tests**: Fast tests that don't execute the brush binary (excludes integration test
//!   binaries like brush-compat-tests, brush-interactive-tests, brush-completion-tests)
//! - **Integration tests**: All workspace tests including unit tests and integration tests that
//!   execute the brush binary
//! - **End-to-end tests**: Real applications' own suites (including bash-completion's), run in
//!   containers; see `e2e/README.md`
//!
//! Both unit and integration tests support optional coverage collection via
//! `cargo-llvm-cov`.

use std::path::{Path, PathBuf};

use anyhow::{Context, Result};
use clap::{Args, Parser, Subcommand};
use xshell::{Shell, cmd};

use crate::common::{BuildProfile, find_target_dir};

/// Integration test binaries that are excluded from unit tests.
/// These tests execute the brush binary and are slower.
const INTEGRATION_TEST_BINARIES: &[&str] = &[
    "brush-compat-tests",
    "brush-interactive-tests",
    "brush-completion-tests",
];

#[cfg(windows)]
const TEST_BINARIES_DISABLED_ON_WINDOWS: &[&str] = &["brush-compat-tests"];

/// Shared arguments for test commands that need a brush binary.
#[derive(Args, Debug, Clone)]
pub struct BinaryArgs {
    /// Path to the brush binary to test. If not specified, uses the binary
    /// from the workspace's target directory based on --profile/--debug/--release.
    #[clap(long, global = true)]
    pub brush_path: Option<PathBuf>,

    /// Build profile to use when auto-detecting the brush binary.
    #[clap(long, short = 'p', value_enum, default_value_t = BuildProfile::Debug, global = true)]
    pub profile: BuildProfile,

    /// Use debug build profile (shorthand for --profile=debug).
    #[clap(long, conflicts_with_all = ["profile", "release"], global = true)]
    pub debug: bool,

    /// Use release build profile (shorthand for --profile=release).
    #[clap(long, conflicts_with_all = ["profile", "debug"], global = true)]
    pub release: bool,
}

impl BinaryArgs {
    /// Resolve the effective build profile, considering --debug/--release shorthands.
    #[must_use]
    pub const fn effective_profile(&self) -> BuildProfile {
        if self.debug {
            BuildProfile::Debug
        } else if self.release {
            BuildProfile::Release
        } else {
            self.profile
        }
    }

    /// Find the brush binary using these arguments.
    #[cfg(unix)]
    pub fn find_brush_binary(&self) -> Result<PathBuf> {
        crate::common::find_brush_binary(self.brush_path.as_ref(), self.effective_profile())
    }
}

/// Run tests.
#[derive(Parser)]
pub struct TestCommand {
    /// Shared binary arguments.
    #[clap(flatten)]
    pub binary_args: BinaryArgs,

    /// Test subcommand.
    #[clap(subcommand)]
    pub subcommand: TestSubcommand,
}

/// Test subcommands.
#[derive(Subcommand, Clone)]
pub enum TestSubcommand {
    /// Run unit tests (fast tests that don't execute the brush binary).
    ///
    /// Excludes integration test binaries: brush-compat-tests, brush-interactive-tests,
    /// brush-completion-tests.
    Unit(UnitTestArgs),

    /// Run all workspace tests (unit + integration tests).
    ///
    /// This includes all tests: unit tests plus integration tests that execute
    /// the brush binary (compat tests, interactive tests, completion tests).
    Integration(IntegrationTestArgs),

    /// Run containerized end-to-end tests against real applications.
    #[cfg(unix)]
    E2e(crate::e2e::E2eArgs),
}

/// Arguments for unit tests.
#[derive(Args, Clone, Default)]
pub struct UnitTestArgs {
    /// Coverage options.
    #[clap(flatten)]
    pub coverage: CoverageArgs,
}

/// Arguments for integration tests.
#[derive(Args, Clone, Default)]
pub struct IntegrationTestArgs {
    /// Coverage options.
    #[clap(flatten)]
    pub coverage: CoverageArgs,

    /// Copy the nextest `JUnit` XML results to this path after the test run.
    /// The copy is performed even if tests fail, so CI can always upload results.
    #[clap(long)]
    pub results_output: Option<PathBuf>,

    /// Build and test against a wasm32-wasip3 target under a WASI runtime
    /// (wasmtime by default). Builds brush for wasm32-wasip3 with its default
    /// features, then runs a subset of integration tests (excluding compat,
    /// interactive, and completion suites) under the WASI launcher. Needs a
    /// toolchain with the wasm32-wasip3 target (Rust 1.100+, or nightly) and
    /// a runtime with WASI 0.3 support (e.g., wasmtime 46+).
    #[clap(long)]
    pub wasi: bool,

    /// Launcher command for the WASI runtime (only used with --wasi).
    /// The first token is resolved against `PATH`; subsequent tokens are
    /// passed as leading arguments before the brush binary path.
    /// Defaults to `wasmtime run -S inherit-env --dir=.::/ --allow-precompiled --`.
    #[clap(long)]
    pub wasi_launcher: Option<String>,

    /// Skip the WASI wasm build step and assume brush.wasm is already
    /// present at the expected path (only used with --wasi).
    #[clap(long)]
    pub skip_wasi_build: bool,
}

/// Arguments for coverage collection.
#[derive(Args, Clone, Default)]
pub struct CoverageArgs {
    /// Collect code coverage during test run.
    #[clap(long)]
    pub coverage: bool,

    /// Output file for coverage report (Cobertura XML format).
    /// Only used when --coverage is specified.
    #[clap(long, short = 'o', default_value = "codecov.xml")]
    pub coverage_output: PathBuf,
}

/// Run a test command.
pub fn run(cmd: &TestCommand, verbose: bool) -> Result<()> {
    let sh = Shell::new()?;

    match &cmd.subcommand {
        TestSubcommand::Unit(args) => run_unit_tests(&sh, &cmd.binary_args, args, verbose),
        TestSubcommand::Integration(args) => {
            run_integration_tests(&sh, &cmd.binary_args, args, verbose)
        }
        #[cfg(unix)]
        TestSubcommand::E2e(args) => crate::e2e::run(&cmd.binary_args, args, verbose),
    }
}

/// Run unit tests (excludes integration test binaries).
///
/// Unit tests are fast tests that don't execute the brush binary.
pub fn run_unit_tests(
    sh: &Shell,
    binary_args: &BinaryArgs,
    args: &UnitTestArgs,
    verbose: bool,
) -> Result<()> {
    let profile = binary_args.effective_profile();
    eprintln!("Running unit tests ({profile:?} profile)...");

    // Build the filter expression to exclude integration test binaries
    let exclusions: Vec<String> = INTEGRATION_TEST_BINARIES
        .iter()
        .map(|name| format!("not binary({name})"))
        .collect();
    let filter_expr = exclusions.join(" and ");

    if args.coverage.coverage {
        run_tests_with_coverage(
            sh,
            profile,
            Some(&filter_expr),
            &args.coverage.coverage_output,
            verbose,
        )
    } else {
        run_nextest(sh, profile, Some(&filter_expr), verbose)?;
        eprintln!("Unit tests passed.");
        Ok(())
    }
}

/// Run all workspace tests (unit + integration).
///
/// This runs all tests in the workspace, including integration tests
/// that execute the brush binary. With `--wasi`, builds brush for
/// wasm32-wasip3 and runs the integration tests under a WASI runtime.
pub fn run_integration_tests(
    sh: &Shell,
    binary_args: &BinaryArgs,
    args: &IntegrationTestArgs,
    verbose: bool,
) -> Result<()> {
    let profile = binary_args.effective_profile();

    if args.wasi {
        if args.coverage.coverage {
            eprintln!("Warning: --coverage is not supported with --wasi and will be ignored.");
        }
        return run_integration_tests_wasi(sh, profile, args, verbose);
    }

    eprintln!("Running integration tests ({profile:?} profile)...");

    #[cfg(windows)]
    let exclusions: Vec<String> = TEST_BINARIES_DISABLED_ON_WINDOWS
        .iter()
        .map(|name| format!("not binary({name})"))
        .collect();
    #[cfg(windows)]
    let filter_expr = exclusions.join(" and ");
    #[cfg(windows)]
    let filter = Some(filter_expr.as_str());

    #[cfg(not(windows))]
    let filter = None;

    let test_result = if args.coverage.coverage {
        run_tests_with_coverage(sh, profile, filter, &args.coverage.coverage_output, verbose)
    } else {
        run_nextest(sh, profile, filter, verbose).map(|()| {
            eprintln!("Integration tests passed.");
        })
    };

    // Copy nextest results if requested (even on test failure, so CI can upload them).
    if let Some(ref output) = args.results_output {
        copy_nextest_results(output)?;
    }

    test_result
}

/// Run the brush integration tests against a wasm32-wasip3 build of brush,
/// executed under a WASI runtime. Builds the wasm module first unless
/// `--skip-wasi-build` is given, then runs the integration tests via nextest
/// with the appropriate environment variables populated for the test harness.
fn run_integration_tests_wasi(
    sh: &Shell,
    profile: BuildProfile,
    args: &IntegrationTestArgs,
    verbose: bool,
) -> Result<()> {
    let is_release = profile == BuildProfile::Release;

    // Build the wasm module unless the caller opts out.
    if !args.skip_wasi_build {
        eprintln!("Building brush for wasm32-wasip3...");
        let mut build_args = vec![
            "build",
            "--target",
            "wasm32-wasip3",
            "-p",
            "brush-shell",
            "--bin",
            "brush",
        ];
        if is_release {
            build_args.push("--release");
        }
        if verbose {
            eprintln!("Running: cargo {}", build_args.join(" "));
        }
        cmd!(sh, "cargo {build_args...}")
            .run()
            .context("failed to build brush for wasm32-wasip3")?;
    }

    // Locate the wasm module that was (or should have been) produced.
    let profile_dir = if is_release { "release" } else { "debug" };
    let wasm_path = find_target_dir()?
        .join("wasm32-wasip3")
        .join(profile_dir)
        .join("brush.wasm");
    let wasm_path = wasm_path.canonicalize().with_context(|| {
        format!(
            "brush.wasm not found at {} — did the build step succeed?",
            wasm_path.display()
        )
    })?;

    // The `--dir=.::/` flag maps the host root filesystem into the WASI
    // sandbox. This is intentionally permissive for testing — tests create
    // temp dirs and need access to fixtures across the filesystem. This is
    // NOT a recommended default for production use of brush under WASI.
    // Pre-compile the wasm module to avoid JIT compilation overhead during
    // parallel test execution. Without this, multiple concurrent wasmtime
    // processes each try to JIT-compile brush.wasm simultaneously, which
    // can exceed test timeouts on CI.
    eprintln!("Pre-compiling brush.wasm...");
    let cwasm_path = wasm_path.with_extension("cwasm");
    {
        let wasm_arg = wasm_path.display().to_string();
        let cwasm_arg = cwasm_path.display().to_string();
        cmd!(sh, "wasmtime compile {wasm_arg} -o {cwasm_arg}")
            .run()
            .context("failed to pre-compile brush.wasm with wasmtime")?;
    }

    // The default launcher includes --allow-precompiled so wasmtime accepts
    // the AOT-compiled .cwasm module without re-compilation, and
    // `-S inherit-env` so the environment the harness sets for each test
    // case reaches brush.
    let launcher = args
        .wasi_launcher
        .as_deref()
        .unwrap_or("wasmtime run -S inherit-env --dir=.::/ --allow-precompiled --");

    eprintln!("Running brush integration tests under WASI...");
    eprintln!("  wasm:     {}", cwasm_path.display());
    eprintln!("  launcher: {launcher}");

    let brush_path_str = cwasm_path.display().to_string();
    let _brush_path = sh.push_env("BRUSH_PATH", &brush_path_str);
    let _brush_launcher = sh.push_env("BRUSH_LAUNCHER", launcher);
    let _brush_platform_tags = sh.push_env("BRUSH_PLATFORM_TAGS", "wasi wasm");

    // Only run the brush integration tests; compat tests require a native binary.
    let filter = "binary(brush-integration-tests)";
    let test_result = run_nextest(sh, profile, Some(filter), verbose);

    // Copy nextest results if requested (even on test failure, so CI can upload them).
    if let Some(ref output) = args.results_output {
        copy_nextest_results(output)?;
    }

    test_result
}

/// Run cargo nextest with optional filter expression.
fn run_nextest(
    sh: &Shell,
    profile: BuildProfile,
    filter_expr: Option<&str>,
    verbose: bool,
) -> Result<()> {
    let mut args = vec!["nextest", "run", "--workspace", "--no-fail-fast"];

    if profile == BuildProfile::Release {
        args.push("--release");
    }

    // Add filter expression if provided
    let filter_value = filter_expr.map(str::to_string);
    if let Some(ref value) = filter_value {
        args.push("-E");
        args.push(value);
    }

    if verbose {
        eprintln!("Running: cargo {}", args.join(" "));
    }

    cmd!(sh, "cargo {args...}").run().context("Tests failed")?;
    Ok(())
}

/// Copy the nextest `JUnit` XML results to the given output path.
fn copy_nextest_results(output: &Path) -> Result<()> {
    let source = find_target_dir()?.join("nextest/default/test-results.xml");
    std::fs::copy(&source, output).with_context(|| {
        format!(
            "Failed to copy nextest results from {} to {}",
            source.display(),
            output.display()
        )
    })?;
    eprintln!("Nextest results copied to: {}", output.display());
    Ok(())
}

/// Run tests with code coverage collection using `cargo-llvm-cov`.
///
/// The coverage workflow:
/// 1. Source environment variables from `cargo llvm-cov show-env`
/// 2. Clean previous coverage data
/// 3. Run tests (continuing even if tests fail to still generate report)
/// 4. Generate Cobertura XML report for CI integration
///
/// Requires `cargo-llvm-cov` to be installed: `cargo install cargo-llvm-cov`
fn run_tests_with_coverage(
    sh: &Shell,
    profile: BuildProfile,
    filter_expr: Option<&str>,
    output: &Path,
    verbose: bool,
) -> Result<()> {
    let output_path = output.display().to_string();

    eprintln!("Running tests with coverage ({profile:?} profile)...");
    eprintln!("Coverage output: {output_path}");

    // Set up llvm-cov environment
    eprintln!("Setting up llvm-cov environment...");
    if verbose {
        eprintln!("Running: cargo llvm-cov show-env --export-prefix");
    }
    let env_output = cmd!(sh, "cargo llvm-cov show-env --export-prefix")
        .read()
        .context("Failed to get llvm-cov environment. Is cargo-llvm-cov installed?")?;

    // Parse and set environment variables from llvm-cov output
    env_output
        .lines()
        .filter_map(|line| line.strip_prefix("export "))
        .filter_map(|rest| rest.split_once('='))
        .for_each(|(k, v)| sh.set_var(k, v.trim_matches(['"', '\''])));

    // Clean previous coverage data
    if verbose {
        eprintln!("Running: cargo llvm-cov clean --workspace");
    }
    cmd!(sh, "cargo llvm-cov clean --workspace")
        .run()
        .context("Failed to clean coverage data")?;

    // Build cargo nextest args
    let mut test_args = vec!["nextest", "run", "--workspace", "--no-fail-fast"];
    if profile == BuildProfile::Release {
        test_args.push("--release");
    }

    // Add filter expression if provided
    let filter_value = filter_expr.map(str::to_string);
    if let Some(ref value) = filter_value {
        test_args.push("-E");
        test_args.push(value);
    }

    if verbose {
        eprintln!("Running: cargo {}", test_args.join(" "));
    }

    // Run tests - let output pass through naturally, but continue on failure to generate coverage
    // report
    let test_result = cmd!(sh, "cargo {test_args...}").run();
    let test_failed = test_result.is_err();

    if test_failed {
        eprintln!("Tests failed, but continuing to generate coverage report...");
    }

    // Generate coverage report (always attempt this)
    eprintln!("Generating coverage report...");
    if verbose {
        eprintln!("Running: cargo llvm-cov report --cobertura --output-path {output_path}");
    }
    cmd!(
        sh,
        "cargo llvm-cov report --cobertura --output-path {output_path}"
    )
    .run()
    .context("Failed to generate coverage report")?;

    eprintln!("Coverage report written to: {output_path}");

    // Now propagate test failure if tests failed
    if test_failed {
        anyhow::bail!("Tests failed (coverage report was still generated)");
    }

    eprintln!("Tests with coverage completed successfully.");
    Ok(())
}