//! Core data model for Unity files
//!
//! This module provides the fundamental types for representing parsed Unity files.
//! Unity files can be Scenes (.unity), Prefabs (.prefab), or Assets (.asset), each
//! with different handling requirements.

use crate::parser::{GuidResolver, PrefabGuidResolver};
use crate::types::FileID;
use log::info;
use sparsey::{Entity, World};
use std::collections::HashMap;
use std::path::{Path, PathBuf};

/// A parsed Unity file - can be a Scene, Prefab, or Asset
#[derive(Debug)]
pub enum UnityFile {
    /// Scene file (.unity) with fully-parsed ECS World
    Scene(UnityScene),
    /// Prefab file (.prefab) with raw YAML for instancing
    Prefab(UnityPrefab),
    /// Asset file (.asset) with raw YAML
    Asset(UnityAsset),
}

impl UnityFile {
    /// Parse a Unity file from the given path
    pub fn from_path(path: impl Into<PathBuf>) -> crate::Result<Self> {
        let path = path.into();
        crate::parser::parse_unity_file(&path)
    }

    /// Get the file path
    pub fn path(&self) -> &PathBuf {
        match self {
            UnityFile::Scene(s) => &s.path,
            UnityFile::Prefab(p) => &p.path,
            UnityFile::Asset(a) => &a.path,
        }
    }

    /// Check if this is a scene
    pub fn is_scene(&self) -> bool {
        matches!(self, UnityFile::Scene(_))
    }

    /// Check if this is a prefab
    pub fn is_prefab(&self) -> bool {
        matches!(self, UnityFile::Prefab(_))
    }

    /// Check if this is an asset
    pub fn is_asset(&self) -> bool {
        matches!(self, UnityFile::Asset(_))
    }
}

/// A Unity scene with fully-parsed ECS World
///
/// Scenes contain GameObjects and Components parsed into a Sparsey ECS world.
/// The entity_map provides mapping from Unity FileIDs to ECS entities.
#[derive(Debug)]
pub struct UnityScene {
    /// Path to the scene file
    pub path: PathBuf,

    /// ECS World containing all entities and components
    pub world: World,

    /// Mapping from Unity FileID to ECS Entity
    pub entity_map: HashMap<FileID, Entity>,
}

impl UnityScene {
    /// Create a new UnityScene
    pub fn new(path: PathBuf, world: World, entity_map: HashMap<FileID, Entity>) -> Self {
        Self {
            path,
            world,
            entity_map,
        }
    }

    /// Get an entity by its Unity FileID
    pub fn get_entity(&self, file_id: FileID) -> Option<Entity> {
        self.entity_map.get(&file_id).copied()
    }
}

/// A Unity prefab with raw YAML for instancing
///
/// Prefabs are kept as raw YAML documents to enable efficient cloning and
/// value overriding during instantiation into scenes.
#[derive(Debug, Clone)]
pub struct UnityPrefab {
    /// Path to the prefab file
    pub path: PathBuf,

    /// Raw YAML documents that make up this prefab
    pub documents: Vec<RawDocument>,
}

impl UnityPrefab {
    /// Create a new UnityPrefab
    pub fn new(path: PathBuf, documents: Vec<RawDocument>) -> Self {
        Self { path, documents }
    }

    /// Get a document by its FileID
    pub fn get_document(&self, file_id: FileID) -> Option<&RawDocument> {
        self.documents.iter().find(|doc| doc.file_id == file_id)
    }

    /// Get all documents of a specific type
    pub fn get_documents_by_type(&self, type_id: u32) -> Vec<&RawDocument> {
        self.documents
            .iter()
            .filter(|doc| doc.type_id == type_id)
            .collect()
    }

    /// Get all documents with a specific class name
    pub fn get_documents_by_class(&self, class_name: &str) -> Vec<&RawDocument> {
        self.documents
            .iter()
            .filter(|doc| doc.class_name == class_name)
            .collect()
    }

    /// Create a new instance of this prefab for spawning into a scene
    ///
    /// This clones the prefab's documents and prepares them for instantiation
    /// with unique FileIDs to avoid collisions.
    ///
    /// # Returns
    /// A `PrefabInstance` that can be customized with overrides and spawned
    ///
    /// # Example
    /// ```ignore
    /// let mut instance = prefab.instantiate(None);
    /// instance.override_value(file_id, "m_Name", "Player1".into())?;
    /// let entities = instance.spawn_into(&mut world, &mut entity_map)?;
    /// ```
    pub fn instantiate(&self, file_id_counter: Option<std::sync::Arc<std::cell::Cell<i64>>>) -> crate::types::PrefabInstance {
        crate::types::PrefabInstance::new(self, file_id_counter)
    }
}

/// A Unity asset file with raw YAML
///
/// Assets (like ScriptableObjects) are handled similarly to prefabs.
#[derive(Debug, Clone)]
pub struct UnityAsset {
    /// Path to the asset file
    pub path: PathBuf,

    /// Raw YAML documents that make up this asset
    pub documents: Vec<RawDocument>,
}

impl UnityAsset {
    /// Create a new UnityAsset
    pub fn new(path: PathBuf, documents: Vec<RawDocument>) -> Self {
        Self { path, documents }
    }

    /// Get a document by its FileID
    pub fn get_document(&self, file_id: FileID) -> Option<&RawDocument> {
        self.documents.iter().find(|doc| doc.file_id == file_id)
    }
}

/// A raw YAML document with Unity metadata
///
/// This represents a single Unity object (GameObject, Component, etc.) with
/// its metadata (type_id, file_id, class_name) and raw YAML content.
///
/// The `yaml` field contains the inner YAML mapping (the contents after the
/// class name wrapper like `GameObject: { ... }`).
#[derive(Debug, Clone)]
pub struct RawDocument {
    /// Unity type ID (from !u!N tag)
    pub type_id: u32,

    /// File ID (from &ID anchor)
    pub file_id: FileID,

    /// Class name (e.g., "GameObject", "Transform", "RectTransform")
    pub class_name: String,

    /// Raw YAML value (inner mapping after class wrapper)
    pub yaml: serde_yaml::Value,

    /// Whether this component is stripped (exists in prefab, not in scene)
    pub is_stripped: bool,
}

impl RawDocument {
    /// Create a new RawDocument
    pub fn new(
        type_id: u32,
        file_id: FileID,
        class_name: String,
        yaml: serde_yaml::Value,
        is_stripped: bool,
    ) -> Self {
        Self {
            type_id,
            file_id,
            class_name,
            yaml,
            is_stripped,
        }
    }

    /// Get the YAML as a mapping, if it is one
    pub fn as_mapping(&self) -> Option<&serde_yaml::Mapping> {
        self.yaml.as_mapping()
    }
}

/// A Unity project with pre-built GUID resolvers for efficient scene parsing
///
/// This struct holds pre-initialized GUID mappings for both MonoBehaviour scripts
/// and prefab files. By building these mappings once at initialization, you can
/// parse multiple scenes efficiently without rescanning the project for each file.
///
/// # Example
///
/// ```no_run
/// use unity_parser::UnityProject;
/// use std::path::Path;
///
/// // Initialize project once - scans entire project for .meta files
/// let project = UnityProject::from_path("/home/user/repos/CBAssets")?;
///
/// // Parse multiple scenes efficiently using pre-built resolvers
/// let scene1 = project.parse_scene("_GameAssets/Scenes/Tiles/10_3.unity")?;
/// let scene2 = project.parse_scene("_GameAssets/Scenes/Tiles/11_5.unity")?;
/// # Ok::<(), unity_parser::Error>(())
/// ```
#[derive(Debug, Clone)]
pub struct UnityProject {
    /// Project root path
    pub root: PathBuf,

    /// Script GUID resolver (MonoBehaviour scripts)
    pub guid_resolver: GuidResolver,

    /// Prefab GUID resolver (Prefab files)
    pub prefab_resolver: PrefabGuidResolver,
}

impl UnityProject {
    /// Create a new UnityProject by scanning the entire project directory
    ///
    /// This scans ALL subdirectories under the project root for .meta files
    /// to build comprehensive GUID mappings for both scripts and prefabs.
    ///
    /// Unlike the individual resolver constructors which only scan Assets/ or
    /// _GameAssets/, this scans the entire project root to find assets in
    /// directories like AssetDumpster/, AssetPacks/, etc.
    ///
    /// # Arguments
    ///
    /// * `root` - Path to the Unity project root directory
    ///
    /// # Example
    ///
    /// ```no_run
    /// use unity_parser::UnityProject;
    ///
    /// let project = UnityProject::from_path("/home/user/repos/CBAssets")?;
    /// println!("Found {} script GUIDs", project.guid_resolver.len());
    /// println!("Found {} prefab GUIDs", project.prefab_resolver.len());
    /// # Ok::<(), unity_parser::Error>(())
    /// ```
    pub fn from_path(root: impl Into<PathBuf>) -> crate::Result<Self> {
        let root = root.into();

        info!("🔍 Initializing Unity project from: {}", root.display());

        // Build script GUID resolver by scanning entire project root
        let guid_resolver = GuidResolver::from_project_root(&root)?;
        info!("   ✓ Script GUID resolver built ({} mappings)", guid_resolver.len());

        // Build prefab GUID resolver by scanning entire project root
        let prefab_resolver = PrefabGuidResolver::from_project_root(&root)?;
        info!("   ✓ Prefab GUID resolver built ({} mappings)", prefab_resolver.len());

        Ok(Self {
            root,
            guid_resolver,
            prefab_resolver,
        })
    }

    /// Parse a Unity scene using the pre-built GUID resolvers
    ///
    /// This is more efficient than `UnityFile::from_path` when parsing multiple
    /// scenes because the GUID resolvers are already initialized.
    ///
    /// # Arguments
    ///
    /// * `path` - Path to the scene file (relative to project root or absolute)
    ///
    /// # Example
    ///
    /// ```no_run
    /// # use unity_parser::UnityProject;
    /// # let project = UnityProject::from_path("/home/user/repos/CBAssets")?;
    /// let scene = project.parse_scene("_GameAssets/Scenes/Tiles/10_3.unity")?;
    /// println!("Scene has {} entities", scene.entity_map.len());
    /// # Ok::<(), unity_parser::Error>(())
    /// ```
    pub fn parse_scene(&self, path: impl AsRef<Path>) -> crate::Result<UnityScene> {
        let path = self.resolve_path(path.as_ref());
        crate::parser::parse_scene_with_project(&path, self)
    }

    /// Parse a Unity scene using the pre-built GUID resolvers with optional type filtering
    ///
    /// # Arguments
    ///
    /// * `path` - Path to the scene file (relative to project root or absolute)
    /// * `type_filter` - Optional filter for Unity types and MonoBehaviour class names
    ///
    /// # Example
    ///
    /// ```no_run
    /// # use unity_parser::{UnityProject, TypeFilter};
    /// # let project = UnityProject::from_path("/home/user/repos/CBAssets")?;
    /// let filter = TypeFilter::new(
    ///     vec!["GameObject", "Transform"],
    ///     vec!["InteractableResource"]
    /// );
    /// let scene = project.parse_scene_filtered("_GameAssets/Scenes/Tiles/10_3.unity", Some(&filter))?;
    /// println!("Scene has {} entities", scene.entity_map.len());
    /// # Ok::<(), unity_parser::Error>(())
    /// ```
    pub fn parse_scene_filtered(
        &self,
        path: impl AsRef<Path>,
        type_filter: Option<&crate::types::TypeFilter>
    ) -> crate::Result<UnityScene> {
        let path = self.resolve_path(path.as_ref());
        crate::parser::parse_scene_with_project_filtered(&path, self, type_filter)
    }

    /// Parse a Unity prefab using the pre-built GUID resolvers
    ///
    /// # Arguments
    ///
    /// * `path` - Path to the prefab file (relative to project root or absolute)
    pub fn parse_prefab(&self, path: impl AsRef<Path>) -> crate::Result<UnityPrefab> {
        let path = self.resolve_path(path.as_ref());
        crate::parser::parse_prefab_with_project(&path, self)
    }

    /// Parse a Unity asset file using the pre-built GUID resolvers
    ///
    /// # Arguments
    ///
    /// * `path` - Path to the asset file (relative to project root or absolute)
    pub fn parse_asset(&self, path: impl AsRef<Path>) -> crate::Result<UnityAsset> {
        let path = self.resolve_path(path.as_ref());
        crate::parser::parse_asset_with_project(&path, self)
    }

    /// Resolve a path (if relative, make it relative to project root)
    fn resolve_path(&self, path: &Path) -> PathBuf {
        if path.is_absolute() {
            path.to_path_buf()
        } else {
            self.root.join(path)
        }
    }
}