//! Defines the semantics that Rojo uses to turn entries on the filesystem into
//! Roblox instances using the instance snapshot subsystem.
//!
//! These modules define how files turn into instances.

#![allow(dead_code)]

mod csv;
mod dir;
mod json;
mod json_model;
mod lua;
mod meta_file;
mod project;
mod rbxm;
mod rbxmx;
mod toml;
mod txt;
mod util;
mod yaml;

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

use anyhow::Context;
use memofs::{IoResultExt, Vfs};
use serde::{Deserialize, Serialize};

use crate::{
    glob::Glob,
    project::DEFAULT_PROJECT_NAMES,
    syncback::{SyncbackReturn, SyncbackSnapshot},
};
use crate::{
    snapshot::{InstanceContext, InstanceSnapshot, SyncRule},
    syncback::validate_file_name,
};

use self::{
    csv::{snapshot_csv, snapshot_csv_init, syncback_csv, syncback_csv_init},
    dir::{snapshot_dir, syncback_dir},
    json::snapshot_json,
    json_model::{snapshot_json_model, syncback_json_model},
    lua::{snapshot_lua, snapshot_lua_init, syncback_lua, syncback_lua_init},
    project::{snapshot_project, syncback_project},
    rbxm::{snapshot_rbxm, syncback_rbxm},
    rbxmx::{snapshot_rbxmx, syncback_rbxmx},
    toml::snapshot_toml,
    txt::{snapshot_txt, syncback_txt},
    yaml::snapshot_yaml,
};

pub use self::{
    lua::ScriptType, project::snapshot_project_node, util::emit_legacy_scripts_default,
    util::PathExt,
};

/// Returns an `InstanceSnapshot` for the provided path.
/// This will inspect the path and find the appropriate middleware for it,
/// taking user-written rules into account. Then, it will attempt to convert
/// the path into an InstanceSnapshot using that middleware.
///
/// If a git filter is active in the context and the path is not acknowledged
/// (i.e., the file hasn't changed since the base git reference), this function
/// returns `Ok(None)` to skip syncing that file.
#[profiling::function]
pub fn snapshot_from_vfs(
    context: &InstanceContext,
    vfs: &Vfs,
    path: &Path,
) -> anyhow::Result<Option<InstanceSnapshot>> {
    let meta = match vfs.metadata(path).with_not_found()? {
        Some(meta) => meta,
        None => return Ok(None),
    };

    // Check if this path is acknowledged by the git filter.
    // If not, skip this path entirely.
    if !context.is_path_acknowledged(path) {
        log::trace!(
            "Skipping path {} (not acknowledged by git filter)",
            path.display()
        );
        return Ok(None);
    }

    if meta.is_dir() {
        let (middleware, dir_name, init_path) = get_dir_middleware(vfs, path)?;
        // TODO: Support user defined init paths
        // If and when we do, make sure to go support it in
        // `Project::set_file_name`, as right now it special-cases
        // `default.project.json` as an `init` path.
        match middleware {
            Middleware::Dir => middleware.snapshot(context, vfs, path, dir_name),
            _ => middleware.snapshot(context, vfs, &init_path, dir_name),
        }
    } else {
        let file_name = path
            .file_name()
            .and_then(|n| n.to_str())
            .with_context(|| format!("file name of {} is invalid", path.display()))?;

        // TODO: Is this even necessary anymore?
        match file_name {
            "init.server.luau" | "init.server.lua" | "init.client.luau" | "init.client.lua"
            | "init.luau" | "init.lua" | "init.csv" => return Ok(None),
            _ => {}
        }

        snapshot_from_path(context, vfs, path)
    }
}

/// Gets the appropriate middleware for a directory by checking for `init`
/// files. This uses an intrinsic priority list and for compatibility,
/// that order should be left unchanged.
///
/// Returns the middleware, the name of the directory, and the path to
/// the init location.
fn get_dir_middleware<'path>(
    vfs: &Vfs,
    dir_path: &'path Path,
) -> anyhow::Result<(Middleware, &'path str, PathBuf)> {
    let dir_name = dir_path
        .file_name()
        .expect("Could not extract directory name")
        .to_str()
        .ok_or_else(|| anyhow::anyhow!("File name was not valid UTF-8: {}", dir_path.display()))?;

    static INIT_PATHS: OnceLock<Vec<(Middleware, &str)>> = OnceLock::new();
    let order = INIT_PATHS.get_or_init(|| {
        vec![
            (Middleware::ModuleScriptDir, "init.luau"),
            (Middleware::ModuleScriptDir, "init.lua"),
            (Middleware::ServerScriptDir, "init.server.luau"),
            (Middleware::ServerScriptDir, "init.server.lua"),
            (Middleware::ClientScriptDir, "init.client.luau"),
            (Middleware::ClientScriptDir, "init.client.lua"),
            (Middleware::CsvDir, "init.csv"),
        ]
    });

    for default_project_name in DEFAULT_PROJECT_NAMES {
        let project_path = dir_path.join(default_project_name);
        if vfs.metadata(&project_path).with_not_found()?.is_some() {
            return Ok((Middleware::Project, dir_name, project_path));
        }
    }

    for (middleware, name) in order {
        let test_path = dir_path.join(name);
        if vfs.metadata(&test_path).with_not_found()?.is_some() {
            return Ok((*middleware, dir_name, test_path));
        }
    }

    Ok((Middleware::Dir, dir_name, dir_path.to_path_buf()))
}

/// Gets a snapshot for a path given an InstanceContext and Vfs, taking
/// user specified sync rules into account.
fn snapshot_from_path(
    context: &InstanceContext,
    vfs: &Vfs,
    path: &Path,
) -> anyhow::Result<Option<InstanceSnapshot>> {
    if let Some(rule) = context.get_user_sync_rule(path) {
        return rule
            .middleware
            .snapshot(context, vfs, path, rule.file_name_for_path(path)?);
    } else {
        for rule in default_sync_rules() {
            if rule.matches(path) {
                return rule.middleware.snapshot(
                    context,
                    vfs,
                    path,
                    rule.file_name_for_path(path)?,
                );
            }
        }
    }
    Ok(None)
}

/// Represents a possible 'transformer' used by Rojo to turn a file system
/// item into a Roblox Instance. Missing from this list is metadata.
/// This is deliberate, as metadata is not a snapshot middleware.
///
/// Directories cannot be used for sync rules so they're ignored by Serde.
#[derive(Debug, Clone, Copy, PartialEq, Deserialize, Serialize)]
#[serde(rename_all = "camelCase")]
pub enum Middleware {
    Csv,
    JsonModel,
    Json,
    ServerScript,
    ClientScript,
    ModuleScript,
    PluginScript,
    LegacyClientScript,
    LegacyServerScript,
    RunContextServerScript,
    RunContextClientScript,
    Project,
    Rbxm,
    Rbxmx,
    Toml,
    Text,
    Yaml,
    Ignore,

    #[serde(skip_deserializing)]
    Dir,
    #[serde(skip_deserializing)]
    ServerScriptDir,
    #[serde(skip_deserializing)]
    ClientScriptDir,
    #[serde(skip_deserializing)]
    ModuleScriptDir,
    #[serde(skip_deserializing)]
    CsvDir,
}

impl Middleware {
    /// Creates a snapshot for the given path from the Middleware with
    /// the provided name.
    ///
    /// When a git filter is active in the context, `ignore_unknown_instances`
    /// will be set to `true` on all generated snapshots to preserve descendants
    /// in Studio that are not tracked by Rojo.
    fn snapshot(
        &self,
        context: &InstanceContext,
        vfs: &Vfs,
        path: &Path,
        name: &str,
    ) -> anyhow::Result<Option<InstanceSnapshot>> {
        let mut output = match self {
            Self::Csv => snapshot_csv(context, vfs, path, name),
            Self::JsonModel => snapshot_json_model(context, vfs, path, name),
            Self::Json => snapshot_json(context, vfs, path, name),
            Self::ServerScript => snapshot_lua(context, vfs, path, name, ScriptType::Server),
            Self::ClientScript => snapshot_lua(context, vfs, path, name, ScriptType::Client),
            Self::ModuleScript => snapshot_lua(context, vfs, path, name, ScriptType::Module),
            Self::PluginScript => snapshot_lua(context, vfs, path, name, ScriptType::Plugin),
            Self::LegacyClientScript => {
                snapshot_lua(context, vfs, path, name, ScriptType::LegacyClient)
            }
            Self::LegacyServerScript => {
                snapshot_lua(context, vfs, path, name, ScriptType::LegacyServer)
            }
            Self::RunContextClientScript => {
                snapshot_lua(context, vfs, path, name, ScriptType::RunContextClient)
            }
            Self::RunContextServerScript => {
                snapshot_lua(context, vfs, path, name, ScriptType::RunContextServer)
            }
            Self::Project => snapshot_project(context, vfs, path, name),
            Self::Rbxm => snapshot_rbxm(context, vfs, path, name),
            Self::Rbxmx => snapshot_rbxmx(context, vfs, path, name),
            Self::Toml => snapshot_toml(context, vfs, path, name),
            Self::Text => snapshot_txt(context, vfs, path, name),
            Self::Yaml => snapshot_yaml(context, vfs, path, name),
            Self::Ignore => Ok(None),

            Self::Dir => snapshot_dir(context, vfs, path, name),
            Self::ServerScriptDir => {
                snapshot_lua_init(context, vfs, path, name, ScriptType::Server)
            }
            Self::ClientScriptDir => {
                snapshot_lua_init(context, vfs, path, name, ScriptType::Client)
            }
            Self::ModuleScriptDir => {
                snapshot_lua_init(context, vfs, path, name, ScriptType::Module)
            }
            Self::CsvDir => snapshot_csv_init(context, vfs, path, name),
        };
        if let Ok(Some(ref mut snapshot)) = output {
            snapshot.metadata.middleware = Some(*self);

            // When git filter is active, force ignore_unknown_instances to true
            // so that we don't delete children in Studio that aren't tracked.
            if context.has_git_filter() {
                snapshot.metadata.ignore_unknown_instances = true;
                // Also apply this recursively to all children
                set_ignore_unknown_instances_recursive(&mut snapshot.children);
            }
        }
        output
    }

    /// Runs the syncback mechanism for the provided middleware given a
    /// SyncbackSnapshot.
    pub fn syncback<'sync>(
        &self,
        snapshot: &SyncbackSnapshot<'sync>,
    ) -> anyhow::Result<SyncbackReturn<'sync>> {
        let file_name = snapshot.path.file_name().and_then(|s| s.to_str());
        if let Some(file_name) = file_name {
            validate_file_name(file_name).with_context(|| {
                format!("cannot create a file or directory with name {file_name}")
            })?;
        }
        match self {
            Middleware::Csv => syncback_csv(snapshot),
            Middleware::JsonModel => syncback_json_model(snapshot),
            Middleware::Json => anyhow::bail!("cannot syncback Json middleware"),
            // Projects are only generated from files that already exist on the
            // file system, so we don't need to pass a file name.
            Middleware::Project => syncback_project(snapshot),
            Middleware::ServerScript => syncback_lua(snapshot),
            Middleware::ClientScript => syncback_lua(snapshot),
            Middleware::ModuleScript => syncback_lua(snapshot),
            Middleware::Rbxm => syncback_rbxm(snapshot),
            Middleware::Rbxmx => syncback_rbxmx(snapshot),
            Middleware::Toml => anyhow::bail!("cannot syncback Toml middleware"),
            Middleware::Text => syncback_txt(snapshot),
            Middleware::Yaml => anyhow::bail!("cannot syncback Yaml middleware"),
            Middleware::Ignore => anyhow::bail!("cannot syncback Ignore middleware"),
            Middleware::Dir => syncback_dir(snapshot),
            Middleware::ServerScriptDir => syncback_lua_init(ScriptType::Server, snapshot),
            Middleware::ClientScriptDir => syncback_lua_init(ScriptType::Client, snapshot),
            Middleware::ModuleScriptDir => syncback_lua_init(ScriptType::Module, snapshot),
            Middleware::CsvDir => syncback_csv_init(snapshot),

            Middleware::PluginScript
            | Middleware::LegacyServerScript
            | Middleware::LegacyClientScript
            | Middleware::RunContextServerScript
            | Middleware::RunContextClientScript => {
                anyhow::bail!("syncback is not implemented for {self:?} yet")
            }
        }
    }

    /// Returns whether this particular middleware would become a directory.
    #[inline]
    pub fn is_dir(&self) -> bool {
        matches!(
            self,
            Middleware::Dir
                | Middleware::ServerScriptDir
                | Middleware::ClientScriptDir
                | Middleware::ModuleScriptDir
                | Middleware::CsvDir
        )
    }

    /// Returns whether this particular middleware sets its own properties.
    /// This applies to things like `JsonModel` and `Project`, since they
    /// set properties without needing a meta.json file.
    ///
    /// It does not cover middleware like `ServerScript` or `Csv` because they
    /// need a meta.json file to set properties that aren't their designated
    /// 'special' properties.
    #[inline]
    pub fn handles_own_properties(&self) -> bool {
        matches!(
            self,
            Middleware::JsonModel | Middleware::Project | Middleware::Rbxm | Middleware::Rbxmx
        )
    }

    /// Attempts to return a middleware that should be used for the given path.
    ///
    /// Returns `Err` only if the Vfs cannot read information about the path.
    pub fn middleware_for_path(
        vfs: &Vfs,
        sync_rules: &[SyncRule],
        path: &Path,
    ) -> anyhow::Result<Option<Self>> {
        let meta = match vfs.metadata(path).with_not_found()? {
            Some(meta) => meta,
            None => return Ok(None),
        };

        if meta.is_dir() {
            let (middleware, _, _) = get_dir_middleware(vfs, path)?;
            Ok(Some(middleware))
        } else {
            for rule in sync_rules.iter().chain(default_sync_rules()) {
                if rule.matches(path) {
                    return Ok(Some(rule.middleware));
                }
            }
            Ok(None)
        }
    }
}

/// Recursively sets `ignore_unknown_instances` to `true` on all children.
/// This is used when git filter is active to ensure we don't delete
/// children in Studio that aren't tracked by Rojo.
fn set_ignore_unknown_instances_recursive(children: &mut [InstanceSnapshot]) {
    for child in children {
        child.metadata.ignore_unknown_instances = true;
        set_ignore_unknown_instances_recursive(&mut child.children);
    }
}

/// A helper for easily defining a SyncRule. Arguments are passed literally
/// to this macro in the order `include`, `middleware`, `suffix`,
/// and `exclude`. Both `suffix` and `exclude` are optional.
///
/// All arguments except `middleware` are expected to be strings.
/// The `middleware` parameter is expected to be a variant of `Middleware`,
/// not including the enum name itself.
macro_rules! sync_rule {
    ($pattern:expr, $middleware:ident) => {
        SyncRule {
            middleware: Middleware::$middleware,
            include: Glob::new($pattern).unwrap(),
            exclude: None,
            suffix: None,
            base_path: PathBuf::new(),
        }
    };
    ($pattern:expr, $middleware:ident, $suffix:expr) => {
        SyncRule {
            middleware: Middleware::$middleware,
            include: Glob::new($pattern).unwrap(),
            exclude: None,
            suffix: Some($suffix.into()),
            base_path: PathBuf::new(),
        }
    };
    ($pattern:expr, $middleware:ident, $suffix:expr, $exclude:expr) => {
        SyncRule {
            middleware: Middleware::$middleware,
            include: Glob::new($pattern).unwrap(),
            exclude: Some(Glob::new($exclude).unwrap()),
            suffix: Some($suffix.into()),
            base_path: PathBuf::new(),
        }
    };
}

/// Defines the 'default' syncing rules that Rojo uses.
/// These do not broadly overlap, but the order matters for some in the case of
/// e.g. JSON models.
pub fn default_sync_rules() -> &'static [SyncRule] {
    static DEFAULT_SYNC_RULES: OnceLock<Vec<SyncRule>> = OnceLock::new();

    DEFAULT_SYNC_RULES.get_or_init(|| {
        vec![
            sync_rule!("*.server.lua", ServerScript, ".server.lua"),
            sync_rule!("*.server.luau", ServerScript, ".server.luau"),
            sync_rule!("*.client.lua", ClientScript, ".client.lua"),
            sync_rule!("*.client.luau", ClientScript, ".client.luau"),
            sync_rule!("*.plugin.lua", PluginScript, ".plugin.lua"),
            sync_rule!("*.plugin.luau", PluginScript, ".plugin.luau"),
            sync_rule!("*.{lua,luau}", ModuleScript),
            sync_rule!("*.project.json", Project, ".project.json"),
            sync_rule!("*.project.jsonc", Project, ".project.jsonc"),
            sync_rule!("*.model.json", JsonModel, ".model.json"),
            sync_rule!("*.model.jsonc", JsonModel, ".model.jsonc"),
            sync_rule!("*.json", Json, ".json", "*.meta.json"),
            sync_rule!("*.jsonc", Json, ".jsonc", "*.meta.jsonc"),
            sync_rule!("*.toml", Toml),
            sync_rule!("*.csv", Csv),
            sync_rule!("*.txt", Text),
            sync_rule!("*.rbxmx", Rbxmx),
            sync_rule!("*.rbxm", Rbxm),
            sync_rule!("*.{yml,yaml}", Yaml),
        ]
    })
}