//! The GUI test runner.
//!
//! This uses the browser-ui-test npm package to use a headless Chrome to
//! exercise the behavior of rendered books. See `CONTRIBUTING.md` for more
//! information.

use serde_json::Value;
use std::fs::read_to_string;
use std::path::{Path, PathBuf};
use std::process::{Command, Output};

fn get_available_browser_ui_test_version_inner(global: bool) -> Option<String> {
    let mut command = Command::new("npm");
    command
        .arg("list")
        .arg("--parseable")
        .arg("--long")
        .arg("--depth=0");
    if global {
        command.arg("--global");
    }
    let stdout = command.output().expect("`npm` command not found").stdout;
    let lines = String::from_utf8_lossy(&stdout);
    lines
        .lines()
        .find_map(|l| l.split(':').nth(1)?.strip_prefix("browser-ui-test@"))
        .map(std::borrow::ToOwned::to_owned)
}

fn get_available_browser_ui_test_version() -> Option<String> {
    get_available_browser_ui_test_version_inner(false)
        .or_else(|| get_available_browser_ui_test_version_inner(true))
}

fn expected_browser_ui_test_version() -> String {
    let content = read_to_string("package.json").expect("failed to read `package.json`");
    let v: Value = serde_json::from_str(&content).expect("failed to parse `package.json`");
    let Some(dependencies) = v.get("dependencies") else {
        panic!("Missing `dependencies` key in `package.json`");
    };
    let Some(browser_ui_test) = dependencies.get("browser-ui-test") else {
        panic!("Missing `browser-ui-test` key in \"dependencies\" object in `package.json`");
    };
    let Value::String(version) = browser_ui_test else {
        panic!("`browser-ui-test` version is not a string");
    };
    version.trim().to_string()
}

fn main() {
    let browser_ui_test_version = expected_browser_ui_test_version();
    match get_available_browser_ui_test_version() {
        Some(version) => {
            if version != browser_ui_test_version {
                eprintln!(
                    "⚠️ Installed version of browser-ui-test (`{version}`) is different than the \
                     one used in the CI (`{browser_ui_test_version}`) You can install this version \
                     using `npm update browser-ui-test` or by using `npm install browser-ui-test\
                     @{browser_ui_test_version}`",
                );
            }
        }
        None => {
            panic!(
                "`browser-ui-test` is not installed. You can install this package using `npm \
                 update browser-ui-test` or by using `npm install browser-ui-test\
                 @{browser_ui_test_version}`",
            );
        }
    }

    let out_dir = Path::new(env!("CARGO_TARGET_TMPDIR")).join("gui");
    build_books(&out_dir);
    run_browser_ui_test(&out_dir);
}

fn build_books(out_dir: &Path) {
    let exe = build_mdbook();
    let root = Path::new(env!("CARGO_MANIFEST_DIR"));
    let books_dir = root.join("tests/gui/books");
    for entry in books_dir.read_dir().unwrap() {
        let entry = entry.unwrap();
        let path = entry.path();
        if !path.is_dir() {
            continue;
        }
        println!("Building `{}`", path.display());
        let mut cmd = Command::new(&exe);
        let output = cmd
            .arg("build")
            .arg("--dest-dir")
            .arg(out_dir.join(path.file_name().unwrap()))
            .arg(&path)
            .output()
            .expect("mdbook should be built");
        check_status(&cmd, &output);
    }
}

fn build_mdbook() -> PathBuf {
    let mut cmd = Command::new("cargo");
    let output = cmd
        .arg("build")
        .output()
        .expect("cargo should be installed");
    check_status(&cmd, &output);
    let target_dir = detect_target_dir();
    target_dir.join("debug/mdbook")
}

fn detect_target_dir() -> PathBuf {
    let mut cmd = Command::new("cargo");
    let output = cmd
        .args(["metadata", "--format-version=1", "--no-deps"])
        .output()
        .expect("cargo should be installed");
    check_status(&cmd, &output);
    let v: serde_json::Value = serde_json::from_slice(&output.stdout).expect("invalid json");
    PathBuf::from(v["target_directory"].as_str().unwrap())
}

fn check_status(cmd: &Command, output: &Output) {
    if !output.status.success() {
        eprintln!("error: `{cmd:?}` failed");
        let stdout = std::str::from_utf8(&output.stdout).expect("stdout is not utf8");
        let stderr = std::str::from_utf8(&output.stderr).expect("stderr is not utf8");
        eprintln!("\n--- stdout\n{stdout}\n--- stderr\n{stderr}");
        std::process::exit(1);
    }
}

fn run_browser_ui_test(out_dir: &Path) {
    let mut command = Command::new("npx");
    let mut doc_path = format!("file://{}", out_dir.display());
    if !doc_path.ends_with('/') {
        doc_path.push('/');
    }
    command
        .arg("browser-ui-test")
        .args(["--variable", "DOC_PATH", doc_path.as_str()])
        .args(["--display-format", "compact"]);

    for arg in std::env::args().skip(1) {
        if arg == "--disable-headless-test" {
            command.arg("--no-headless");
        } else if arg.starts_with("--") {
            command.arg(arg);
        } else {
            command.args(["--filter", arg.as_str()]);
        }
    }

    let test_dir = "tests/gui";
    command.args(["--test-folder", test_dir]);

    // Then we run the GUI tests on it.
    let status = command.status().expect("failed to get command output");
    assert!(status.success(), "{status:?}");
}