use crate::state::SessionState;
use crate::store::StoreOps;
use serde::Serialize;
use serde_json::json;
use std::fs;
use std::path::PathBuf;

const KEY_LAST_PROJECT: &str = "last_project_path";
const KEY_SELECTED_MODEL: &str = "selected_model";
const KEY_KNOWN_PROJECTS: &str = "known_projects";

/// Resolves a relative path against the active project root (pure function for testing).
/// Returns error if path attempts traversal (..).
fn resolve_path_impl(root: PathBuf, relative_path: &str) -> Result<PathBuf, String> {
    if relative_path.contains("..") {
        return Err("Security Violation: Directory traversal ('..') is not allowed.".to_string());
    }

    Ok(root.join(relative_path))
}

/// Resolves a relative path against the active project root.
/// Returns error if no project is open or if path attempts traversal (..).
fn resolve_path(state: &SessionState, relative_path: &str) -> Result<PathBuf, String> {
    let root = state.get_project_root()?;
    resolve_path_impl(root, relative_path)
}

/// Validate that a path exists and is a directory (pure function for testing)
async fn validate_project_path(path: PathBuf) -> Result<(), String> {
    tokio::task::spawn_blocking(move || {
        if !path.exists() {
            return Err(format!("Path does not exist: {}", path.display()));
        }
        if !path.is_dir() {
            return Err(format!("Path is not a directory: {}", path.display()));
        }
        Ok(())
    })
    .await
    .map_err(|e| format!("Task failed: {}", e))?
}

pub async fn open_project(
    path: String,
    state: &SessionState,
    store: &dyn StoreOps,
) -> Result<String, String> {
    let p = PathBuf::from(&path);

    validate_project_path(p.clone()).await?;

    {
        let mut root = state.project_root.lock().map_err(|e| e.to_string())?;
        *root = Some(p);
    }

    store.set(KEY_LAST_PROJECT, json!(path));

    let mut known_projects = get_known_projects(store)?;

    known_projects.retain(|p| p != &path);
    known_projects.insert(0, path.clone());
    store.set(KEY_KNOWN_PROJECTS, json!(known_projects));

    store.save()?;

    Ok(path)
}

pub fn close_project(state: &SessionState, store: &dyn StoreOps) -> Result<(), String> {
    {
        let mut root = state.project_root.lock().map_err(|e| e.to_string())?;
        *root = None;
    }

    store.delete(KEY_LAST_PROJECT);
    store.save()?;

    Ok(())
}

pub fn get_current_project(
    state: &SessionState,
    store: &dyn StoreOps,
) -> Result<Option<String>, String> {
    {
        let root = state.project_root.lock().map_err(|e| e.to_string())?;
        if let Some(path) = &*root {
            return Ok(Some(path.to_string_lossy().to_string()));
        }
    }

    if let Some(path_str) = store
        .get(KEY_LAST_PROJECT)
        .as_ref()
        .and_then(|val| val.as_str())
    {
        let p = PathBuf::from(path_str);
        if p.exists() && p.is_dir() {
            let mut root = state.project_root.lock().map_err(|e| e.to_string())?;
            *root = Some(p);
            return Ok(Some(path_str.to_string()));
        }
    }

    Ok(None)
}

pub fn get_known_projects(store: &dyn StoreOps) -> Result<Vec<String>, String> {
    let projects = store
        .get(KEY_KNOWN_PROJECTS)
        .and_then(|val| val.as_array().cloned())
        .unwrap_or_default()
        .into_iter()
        .filter_map(|val| val.as_str().map(|s| s.to_string()))
        .collect();

    Ok(projects)
}

pub fn get_model_preference(store: &dyn StoreOps) -> Result<Option<String>, String> {
    if let Some(model) = store
        .get(KEY_SELECTED_MODEL)
        .as_ref()
        .and_then(|val| val.as_str())
    {
        return Ok(Some(model.to_string()));
    }
    Ok(None)
}

pub fn set_model_preference(model: String, store: &dyn StoreOps) -> Result<(), String> {
    store.set(KEY_SELECTED_MODEL, json!(model));
    store.save()?;
    Ok(())
}

async fn read_file_impl(full_path: PathBuf) -> Result<String, String> {
    tokio::task::spawn_blocking(move || {
        fs::read_to_string(&full_path).map_err(|e| format!("Failed to read file: {}", e))
    })
    .await
    .map_err(|e| format!("Task failed: {}", e))?
}

pub async fn read_file(path: String, state: &SessionState) -> Result<String, String> {
    let full_path = resolve_path(state, &path)?;
    read_file_impl(full_path).await
}

async fn write_file_impl(full_path: PathBuf, content: String) -> Result<(), String> {
    tokio::task::spawn_blocking(move || {
        if let Some(parent) = full_path.parent() {
            fs::create_dir_all(parent)
                .map_err(|e| format!("Failed to create directories: {}", e))?;
        }

        fs::write(&full_path, content).map_err(|e| format!("Failed to write file: {}", e))
    })
    .await
    .map_err(|e| format!("Task failed: {}", e))?
}

pub async fn write_file(path: String, content: String, state: &SessionState) -> Result<(), String> {
    let full_path = resolve_path(state, &path)?;
    write_file_impl(full_path, content).await
}

#[derive(Serialize, Debug, poem_openapi::Object)]
pub struct FileEntry {
    pub name: String,
    pub kind: String,
}

async fn list_directory_impl(full_path: PathBuf) -> Result<Vec<FileEntry>, String> {
    tokio::task::spawn_blocking(move || {
        let entries = fs::read_dir(&full_path).map_err(|e| format!("Failed to read dir: {}", e))?;

        let mut result = Vec::new();
        for entry in entries {
            let entry = entry.map_err(|e| e.to_string())?;
            let ft = entry.file_type().map_err(|e| e.to_string())?;
            let name = entry.file_name().to_string_lossy().to_string();

            result.push(FileEntry {
                name,
                kind: if ft.is_dir() {
                    "dir".to_string()
                } else {
                    "file".to_string()
                },
            });
        }

        result.sort_by(|a, b| match (a.kind.as_str(), b.kind.as_str()) {
            ("dir", "file") => std::cmp::Ordering::Less,
            ("file", "dir") => std::cmp::Ordering::Greater,
            _ => a.name.cmp(&b.name),
        });

        Ok(result)
    })
    .await
    .map_err(|e| format!("Task failed: {}", e))?
}

pub async fn list_directory(path: String, state: &SessionState) -> Result<Vec<FileEntry>, String> {
    let full_path = resolve_path(state, &path)?;
    list_directory_impl(full_path).await
}