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

use maplit::hashmap;
use memofs::{IoResultExt, Vfs};
use rbx_dom_weak::RbxValue;

use crate::snapshot::{InstanceContext, InstanceMetadata, InstanceSnapshot};

use super::{
    dir::SnapshotDir,
    meta_file::AdjacentMetadata,
    middleware::{SnapshotInstanceResult, SnapshotMiddleware},
    util::match_trailing,
};

pub struct SnapshotLua;

impl SnapshotMiddleware for SnapshotLua {
    fn from_vfs(context: &InstanceContext, vfs: &Vfs, path: &Path) -> SnapshotInstanceResult {
        let file_name = path.file_name().unwrap().to_string_lossy();

        // These paths alter their parent instance, so we don't need to turn
        // them into a script instance here.
        match &*file_name {
            "init.lua" | "init.server.lua" | "init.client.lua" => return Ok(None),
            _ => {}
        }

        let meta = vfs.metadata(path)?;

        if meta.is_file() {
            snapshot_lua_file(context, vfs, path)
        } else {
            // At this point, our entry is definitely a directory!

            if let Some(snapshot) = snapshot_init(context, vfs, path, "init.lua")? {
                // An `init.lua` file turns its parent into a ModuleScript
                Ok(Some(snapshot))
            } else if let Some(snapshot) = snapshot_init(context, vfs, path, "init.server.lua")? {
                // An `init.server.lua` file turns its parent into a Script
                Ok(Some(snapshot))
            } else if let Some(snapshot) = snapshot_init(context, vfs, path, "init.client.lua")? {
                // An `init.client.lua` file turns its parent into a LocalScript
                Ok(Some(snapshot))
            } else {
                Ok(None)
            }
        }
    }
}

/// Core routine for turning Lua files into snapshots.
fn snapshot_lua_file(context: &InstanceContext, vfs: &Vfs, path: &Path) -> SnapshotInstanceResult {
    let file_name = path.file_name().unwrap().to_string_lossy();

    let (class_name, instance_name) = if let Some(name) = match_trailing(&file_name, ".server.lua")
    {
        ("Script", name)
    } else if let Some(name) = match_trailing(&file_name, ".client.lua") {
        ("LocalScript", name)
    } else if let Some(name) = match_trailing(&file_name, ".lua") {
        ("ModuleScript", name)
    } else {
        return Ok(None);
    };

    let contents = vfs.read(path)?;
    let contents_str = str::from_utf8(&contents)
        // TODO: Turn into error type
        .expect("File content was not valid UTF-8")
        .to_string();

    let meta_path = path.with_file_name(format!("{}.meta.json", instance_name));

    let mut snapshot = InstanceSnapshot::new()
        .name(instance_name)
        .class_name(class_name)
        .properties(hashmap! {
            "Source".to_owned() => RbxValue::String {
                value: contents_str,
            },
        })
        .metadata(
            InstanceMetadata::new()
                .instigating_source(path)
                .relevant_paths(vec![path.to_path_buf(), meta_path.clone()])
                .context(context),
        );

    if let Some(meta_contents) = vfs.read(&meta_path).with_not_found()? {
        let mut metadata = AdjacentMetadata::from_slice(&meta_contents, &meta_path)?;
        metadata.apply_all(&mut snapshot);
    }

    Ok(Some(snapshot))
}

/// Attempts to snapshot an 'init' Lua script contained inside of a folder with
/// the given name.
///
/// Scripts named `init.lua`, `init.server.lua`, or `init.client.lua` usurp
/// their parents, which acts similarly to `__init__.py` from the Python world.
fn snapshot_init(
    context: &InstanceContext,
    vfs: &Vfs,
    folder_path: &Path,
    init_name: &str,
) -> SnapshotInstanceResult {
    let init_path = folder_path.join(init_name);

    if vfs.metadata(&init_path).with_not_found()?.is_some() {
        if let Some(dir_snapshot) = SnapshotDir::from_vfs(context, vfs, folder_path)? {
            if let Some(mut init_snapshot) = snapshot_lua_file(context, vfs, &init_path)? {
                if dir_snapshot.class_name != "Folder" {
                    panic!(
                        "init.lua, init.server.lua, and init.client.lua can \
                         only be used if the instance produced by the parent \
                         directory would be a Folder."
                    );
                }

                init_snapshot.name = dir_snapshot.name;
                init_snapshot.children = dir_snapshot.children;
                init_snapshot.metadata = dir_snapshot.metadata;

                return Ok(Some(init_snapshot));
            }
        }
    }

    Ok(None)
}

#[cfg(test)]
mod test {
    use super::*;

    use memofs::{InMemoryFs, VfsSnapshot};

    #[test]
    fn module_from_vfs() {
        let mut imfs = InMemoryFs::new();
        imfs.load_snapshot("/foo.lua", VfsSnapshot::file("Hello there!"))
            .unwrap();

        let mut vfs = Vfs::new(imfs);

        let instance_snapshot =
            SnapshotLua::from_vfs(&InstanceContext::default(), &mut vfs, Path::new("/foo.lua"))
                .unwrap()
                .unwrap();

        insta::assert_yaml_snapshot!(instance_snapshot);
    }

    #[test]
    fn server_from_vfs() {
        let mut imfs = InMemoryFs::new();
        imfs.load_snapshot("/foo.server.lua", VfsSnapshot::file("Hello there!"))
            .unwrap();

        let mut vfs = Vfs::new(imfs);

        let instance_snapshot = SnapshotLua::from_vfs(
            &InstanceContext::default(),
            &mut vfs,
            Path::new("/foo.server.lua"),
        )
        .unwrap()
        .unwrap();

        insta::assert_yaml_snapshot!(instance_snapshot);
    }

    #[test]
    fn client_from_vfs() {
        let mut imfs = InMemoryFs::new();
        imfs.load_snapshot("/foo.client.lua", VfsSnapshot::file("Hello there!"))
            .unwrap();

        let mut vfs = Vfs::new(imfs);

        let instance_snapshot = SnapshotLua::from_vfs(
            &InstanceContext::default(),
            &mut vfs,
            Path::new("/foo.client.lua"),
        )
        .unwrap()
        .unwrap();

        insta::assert_yaml_snapshot!(instance_snapshot);
    }

    #[test]
    fn init_module_from_vfs() {
        let mut imfs = InMemoryFs::new();
        imfs.load_snapshot(
            "/root",
            VfsSnapshot::dir(hashmap! {
                "init.lua" => VfsSnapshot::file("Hello!"),
            }),
        )
        .unwrap();

        let mut vfs = Vfs::new(imfs);

        let instance_snapshot =
            SnapshotLua::from_vfs(&InstanceContext::default(), &mut vfs, Path::new("/root"))
                .unwrap()
                .unwrap();

        insta::assert_yaml_snapshot!(instance_snapshot);
    }

    #[test]
    fn module_with_meta() {
        let mut imfs = InMemoryFs::new();
        imfs.load_snapshot("/foo.lua", VfsSnapshot::file("Hello there!"))
            .unwrap();
        imfs.load_snapshot(
            "/foo.meta.json",
            VfsSnapshot::file(
                r#"
                    {
                        "ignoreUnknownInstances": true
                    }
                "#,
            ),
        )
        .unwrap();

        let mut vfs = Vfs::new(imfs);

        let instance_snapshot =
            SnapshotLua::from_vfs(&InstanceContext::default(), &mut vfs, Path::new("/foo.lua"))
                .unwrap()
                .unwrap();

        insta::assert_yaml_snapshot!(instance_snapshot);
    }

    #[test]
    fn script_with_meta() {
        let mut imfs = InMemoryFs::new();
        imfs.load_snapshot("/foo.server.lua", VfsSnapshot::file("Hello there!"))
            .unwrap();
        imfs.load_snapshot(
            "/foo.meta.json",
            VfsSnapshot::file(
                r#"
                    {
                        "ignoreUnknownInstances": true
                    }
                "#,
            ),
        )
        .unwrap();

        let mut vfs = Vfs::new(imfs);

        let instance_snapshot = SnapshotLua::from_vfs(
            &InstanceContext::default(),
            &mut vfs,
            Path::new("/foo.server.lua"),
        )
        .unwrap()
        .unwrap();

        insta::assert_yaml_snapshot!(instance_snapshot);
    }

    #[test]
    fn script_disabled() {
        let mut imfs = InMemoryFs::new();
        imfs.load_snapshot("/bar.server.lua", VfsSnapshot::file("Hello there!"))
            .unwrap();
        imfs.load_snapshot(
            "/bar.meta.json",
            VfsSnapshot::file(
                r#"
                    {
                        "properties": {
                            "Disabled": true
                        }
                    }
                "#,
            ),
        )
        .unwrap();

        let mut vfs = Vfs::new(imfs);

        let instance_snapshot = SnapshotLua::from_vfs(
            &InstanceContext::default(),
            &mut vfs,
            Path::new("/bar.server.lua"),
        )
        .unwrap()
        .unwrap();

        insta::with_settings!({ sort_maps => true }, {
            insta::assert_yaml_snapshot!(instance_snapshot);
        });
    }
}