//! Build -> Syncback -> Rebuild roundtrip tests.
//!
//! These tests verify that:
//! 1. Building a project to rbxl
//! 2. Syncing back to a fresh directory
//! 3. Rebuilding from the syncback result
//!
//! Produces semantically identical output. This validates that the syncback
//! system correctly reconstructs project structure from binary place files.

use std::collections::HashMap;
use std::{fs, path::Path};

use rbx_dom_weak::{ustr, WeakDom};
use tempfile::tempdir;

use crate::rojo_test::io_util::BUILD_TESTS_PATH;
use crate::rojo_test::roundtrip_util::{
    copy_project_dir, ensure_project_dirs_exist, run_rojo_build, run_rojo_syncback_clean,
};

/// Generate roundtrip tests for build-test projects.
///
/// Each test:
/// 1. Builds the project to an rbxl file
/// 2. Creates a fresh directory with just the project file
/// 3. Syncs back from the rbxl to the fresh directory
/// 4. Rebuilds from the syncback result
/// 5. Compares the two rbxl files for semantic equality
macro_rules! roundtrip_tests {
    ($($test_name:ident),* $(,)?) => {$(
        #[test]
        fn $test_name() {
            run_roundtrip_test(stringify!($test_name));
        }
    )*};
}

fn run_roundtrip_test(build_test_name: &str) {
    let _ = env_logger::try_init();

    let project_path = Path::new(BUILD_TESTS_PATH).join(build_test_name);

    // 1. Build original project -> rbxm (model format, not place)
    let (_tmp1, original_rbxm) = run_rojo_build(&project_path, "original.rbxm");

    // 2. Create fresh syncback target with full project structure
    let syncback_dir = tempdir().expect("Failed to create temp dir");
    copy_project_dir(&project_path, syncback_dir.path());

    // 3. Syncback from rbxm to directory
    assert!(
        run_rojo_syncback_clean(syncback_dir.path(), &original_rbxm),
        "Syncback should succeed for {}",
        build_test_name
    );

    // 3b. Ensure base project directories still exist after syncback.
    // Clean mode may remove directories that only contain meta files or .gitkeep,
    // but the project still needs them for the rebuild.
    ensure_project_dirs_exist(syncback_dir.path());

    // 4. Build from syncback result -> rbxm
    let (_tmp2, roundtrip_rbxm) = run_rojo_build(syncback_dir.path(), "roundtrip.rbxm");

    // 5. Compare both rbxm files (semantic comparison)
    assert_rbx_equal(&original_rbxm, &roundtrip_rbxm, build_test_name);
}

/// Compare two rbxl files for semantic equality.
///
/// This compares the instance trees, checking that all instances have the same
/// names, class names, and properties (excluding transient properties like Ref).
fn assert_rbx_equal(file_a: &Path, file_b: &Path, test_name: &str) {
    let data_a = fs::read(file_a).expect("Failed to read original rbxl");
    let data_b = fs::read(file_b).expect("Failed to read roundtrip rbxl");

    let dom_a = rbx_binary::from_reader(data_a.as_slice()).expect("Failed to parse original rbxl");
    let dom_b = rbx_binary::from_reader(data_b.as_slice()).expect("Failed to parse roundtrip rbxl");

    // Compare the root's children (DataModel children)
    compare_children(
        &dom_a,
        dom_a.root_ref(),
        &dom_b,
        dom_b.root_ref(),
        test_name,
    );
}

/// Recursively compare children of two instances.
///
/// Uses sorted Vec-based comparison (not HashMap) so that duplicate-named
/// children are correctly handled. HashMap would silently overwrite entries
/// sharing a name, making the test blind to lost duplicates.
fn compare_children(
    dom_a: &WeakDom,
    ref_a: rbx_dom_weak::types::Ref,
    dom_b: &WeakDom,
    ref_b: rbx_dom_weak::types::Ref,
    test_name: &str,
) {
    let inst_a = dom_a.get_by_ref(ref_a).expect("Instance A should exist");
    let inst_b = dom_b.get_by_ref(ref_b).expect("Instance B should exist");

    let children_a = inst_a.children();
    let children_b = inst_b.children();

    if children_a.len() != children_b.len() {
        let names_a: Vec<&str> = children_a
            .iter()
            .filter_map(|r| dom_a.get_by_ref(*r).map(|i| i.name.as_str()))
            .collect();
        let names_b: Vec<&str> = children_b
            .iter()
            .filter_map(|r| dom_b.get_by_ref(*r).map(|i| i.name.as_str()))
            .collect();
        panic!(
            "[{}] Child count mismatch under '{}': original has {} children {:?}, \
             roundtrip has {} children {:?}",
            test_name,
            inst_a.name,
            children_a.len(),
            names_a,
            children_b.len(),
            names_b,
        );
    }

    let mut pairs_a: Vec<(&str, rbx_dom_weak::types::Ref)> = children_a
        .iter()
        .filter_map(|&r| dom_a.get_by_ref(r).map(|i| (i.name.as_str(), r)))
        .collect();
    let mut pairs_b: Vec<(&str, rbx_dom_weak::types::Ref)> = children_b
        .iter()
        .filter_map(|&r| dom_b.get_by_ref(r).map(|i| (i.name.as_str(), r)))
        .collect();

    pairs_a.sort_by_key(|(name, _)| *name);
    pairs_b.sort_by_key(|(name, _)| *name);

    for (i, ((name_a, ref_child_a), (name_b, ref_child_b))) in
        pairs_a.iter().zip(pairs_b.iter()).enumerate()
    {
        if name_a != name_b {
            panic!(
                "[{}] Child name mismatch under '{}' at sorted index {}: \
                 original='{}', roundtrip='{}'",
                test_name, inst_a.name, i, name_a, name_b,
            );
        }

        let child_a = dom_a.get_by_ref(*ref_child_a).unwrap();
        let child_b = dom_b.get_by_ref(*ref_child_b).unwrap();

        if child_a.class != child_b.class {
            panic!(
                "[{}] Class mismatch for '{}' (sorted index {}): original={}, roundtrip={}",
                test_name, name_a, i, child_a.class, child_b.class
            );
        }

        compare_properties(child_a, child_b, test_name);

        compare_children(dom_a, *ref_child_a, dom_b, *ref_child_b, test_name);
    }
}

/// Compare properties of two instances.
///
/// Focuses on properties that matter for roundtrip correctness:
/// - Source (for scripts)
/// - Value (for value types)
/// - Other serializable properties
fn compare_properties(
    inst_a: &rbx_dom_weak::Instance,
    inst_b: &rbx_dom_weak::Instance,
    test_name: &str,
) {
    // Check Source property for scripts
    if let (Some(source_a), Some(source_b)) = (
        inst_a.properties.get(&ustr("Source")),
        inst_b.properties.get(&ustr("Source")),
    ) {
        if source_a != source_b {
            panic!(
                "[{}] Source property differs for '{}' ({}):\nOriginal: {:?}\nRoundtrip: {:?}",
                test_name, inst_a.name, inst_a.class, source_a, source_b
            );
        }
    }

    // Check Value property for value types
    if let (Some(value_a), Some(value_b)) = (
        inst_a.properties.get(&ustr("Value")),
        inst_b.properties.get(&ustr("Value")),
    ) {
        if value_a != value_b {
            panic!(
                "[{}] Value property differs for '{}' ({}):\nOriginal: {:?}\nRoundtrip: {:?}",
                test_name, inst_a.name, inst_a.class, value_a, value_b
            );
        }
    }

    // Check Attributes if present
    if let (Some(attrs_a), Some(attrs_b)) = (
        inst_a.properties.get(&ustr("Attributes")),
        inst_b.properties.get(&ustr("Attributes")),
    ) {
        if attrs_a != attrs_b {
            panic!(
                "[{}] Attributes differ for '{}' ({}):\nOriginal: {:?}\nRoundtrip: {:?}",
                test_name, inst_a.name, inst_a.class, attrs_a, attrs_b
            );
        }
    }

    // Check Tags if present
    if let (Some(tags_a), Some(tags_b)) = (
        inst_a.properties.get(&ustr("Tags")),
        inst_b.properties.get(&ustr("Tags")),
    ) {
        if tags_a != tags_b {
            panic!(
                "[{}] Tags differ for '{}' ({}):\nOriginal: {:?}\nRoundtrip: {:?}",
                test_name, inst_a.name, inst_a.class, tags_a, tags_b
            );
        }
    }
}

// =============================================================================
// ROUNDTRIP TESTS
// =============================================================================
//
// These are build-test projects that should roundtrip cleanly through
// build -> syncback -> rebuild.
//
// Some projects are excluded because they:
// - Use sync rules with custom extensions (sync_rule_* projects)
// - Have CSV files that may not roundtrip identically
// - Have special project configurations that affect syncback

roundtrip_tests! {
    // Basic script types
    client_in_folder,
    client_init,
    module_in_folder,
    module_init,
    server_in_folder,
    server_init,

    // Nested structures
    deep_nesting,
    init_with_children,

    // Meta files and properties
    // Note: init_meta_class_name and init_meta_properties are tested separately
    // below with #[ignore] because they have meta-only directories
    script_meta_disabled,

    // JSON models
    json_model_in_folder,
    json_model_legacy_name,

    // Text files
    txt,
    txt_in_folder,

    // Binary models (rbxm/rbxmx)
    rbxm_in_folder,
    rbxmx_in_folder,
    // Note: rbxmx_ref is tested separately below with #[ignore] because
    // Ref IDs differ between builds (expected behavior)

    // Composed projects
    project_composed_default,
    project_composed_file,
    project_root_name,

    // Special cases
    attributes,
    gitkeep,
    optional,
    weldconstraint,

    // Service inference
    // Note: infer_service_name is tested separately below with #[ignore]
    // because it has project-only instances
    infer_starter_player,

    // Issue regression tests
    issue_546,

    // Slugified names and metadata overrides
    meta_name_override,
    model_json_name_override,
    dedup_suffix_with_meta,
}

// =============================================================================
// TESTS WITH KNOWN LIMITATIONS
// =============================================================================

/// Test for project with meta-only directory that sets className.
///
/// IGNORED: This project has `$path: "Lighting"` pointing to a directory that
/// only contains `init.meta.json5` (which sets className to Lighting). Clean mode
/// removes the meta file as it has no script content, then `ensure_project_dirs_exist`
/// recreates it as an empty directory. The rebuild then creates a Folder instead
/// of Lighting because the className info is lost.
///
/// This is expected behavior for clean mode - meta files that only set class/properties
/// (without script content) are not preserved during roundtrip.
#[test]
#[ignore = "Clean mode removes meta-only directories, losing className info"]
fn init_meta_class_name() {
    run_roundtrip_test("init_meta_class_name");
}

/// Test for project with meta-only directory that sets properties.
///
/// IGNORED: Same issue as init_meta_class_name - the meta file sets properties
/// but has no script content, so clean mode removes it.
#[test]
#[ignore = "Clean mode removes meta-only directories, losing properties info"]
fn init_meta_properties() {
    run_roundtrip_test("init_meta_properties");
}

/// Test for project with instances defined only in the project file.
///
/// IGNORED: The project defines HttpService directly in the project file without
/// any `$path`. This instance doesn't get serialized to the rbxm (it has no content),
/// so syncback fails when it can't find HttpService in the input file.
#[test]
#[ignore = "Project-only instances (without $path) don't exist in rbxm"]
fn infer_service_name() {
    run_roundtrip_test("infer_service_name");
}

/// Test for rbxmx files with Ref properties (ObjectValue).
///
/// IGNORED: Ref property IDs are internal identifiers that differ between builds.
/// This is expected behavior - Refs point to other instances by internal ID, and
/// those IDs are regenerated each time the file is built.
#[test]
#[ignore = "Ref property IDs differ between builds (expected)"]
fn rbxmx_ref() {
    run_roundtrip_test("rbxmx_ref");
}

// =============================================================================
// SYNCBACK IDEMPOTENCY TEST
// =============================================================================

/// Build -> syncback -> syncback again. The second syncback must produce
/// zero filesystem changes (i.e., the result is identical to the first).
/// This validates that syncback output is stable and self-consistent.
#[test]
fn syncback_idempotency() {
    let _ = env_logger::try_init();

    // Use dedup_suffix_with_meta as it exercises slugified names + meta
    let project_path = Path::new(BUILD_TESTS_PATH).join("dedup_suffix_with_meta");

    // 1. Build original -> rbxm
    let (_tmp1, original_rbxm) = run_rojo_build(&project_path, "original.rbxm");

    // 2. First syncback
    let first_dir = tempdir().expect("Failed to create temp dir");
    copy_project_dir(&project_path, first_dir.path());
    assert!(
        run_rojo_syncback_clean(first_dir.path(), &original_rbxm),
        "First syncback should succeed"
    );
    ensure_project_dirs_exist(first_dir.path());

    // Snapshot all files after first syncback
    let first_snapshot = snapshot_dir(first_dir.path());

    // 3. Build from first syncback result -> rbxm
    let (_tmp2, first_rbxm) = run_rojo_build(first_dir.path(), "first.rbxm");

    // 4. Second syncback (into a copy of the first syncback result)
    let second_dir = tempdir().expect("Failed to create temp dir");
    copy_project_dir(first_dir.path(), second_dir.path());
    assert!(
        run_rojo_syncback_clean(second_dir.path(), &first_rbxm),
        "Second syncback should succeed"
    );
    ensure_project_dirs_exist(second_dir.path());

    // 5. Snapshot all files after second syncback
    let second_snapshot = snapshot_dir(second_dir.path());

    // 6. Compare snapshots — must be identical
    assert_eq!(
        first_snapshot.len(),
        second_snapshot.len(),
        "File count should be identical between first and second syncback.\n\
         First: {:?}\nSecond: {:?}",
        first_snapshot.keys().collect::<Vec<_>>(),
        second_snapshot.keys().collect::<Vec<_>>(),
    );

    for (path, first_content) in &first_snapshot {
        let second_content = second_snapshot.get(path).unwrap_or_else(|| {
            panic!(
                "File {:?} exists after first syncback but not after second",
                path
            )
        });
        assert_eq!(
            first_content, second_content,
            "File {:?} changed between first and second syncback",
            path
        );
    }
}

/// Snapshot all files under a directory into a map of relative_path -> contents.
fn snapshot_dir(root: &Path) -> HashMap<String, Vec<u8>> {
    let mut result = HashMap::new();
    snapshot_dir_inner(root, root, &mut result);
    result
}

fn snapshot_dir_inner(root: &Path, current: &Path, map: &mut HashMap<String, Vec<u8>>) {
    if let Ok(entries) = fs::read_dir(current) {
        for entry in entries.flatten() {
            let path = entry.path();
            if path.is_dir() {
                snapshot_dir_inner(root, &path, map);
            } else {
                let relative = path
                    .strip_prefix(root)
                    .unwrap()
                    .to_string_lossy()
                    .replace('\\', "/");
                if let Ok(content) = fs::read(&path) {
                    map.insert(relative, content);
                }
            }
        }
    }
}

// =============================================================================
// WINDOWS RESERVED NAME ROUNDTRIP TEST
// =============================================================================

/// Instances named after Windows reserved names (CON, PRN) should round-trip
/// correctly: slugified on disk, real name in meta, rebuild produces correct
/// instance names.
#[test]
fn reserved_name_roundtrip() {
    run_roundtrip_test("reserved_name_override");
}