//! DEX API endpoints.
//!
//! REST endpoints for decentralized exchange operations:
//! - Market data and orderbook
//! - Spot trading
//! - Perpetual futures
//! - Liquidity provision

use axum::{
    extract::{Path, Query, State},
    routing::{delete, get, post},
    Json, Router,
};
use serde::{Deserialize, Serialize};

use crate::{
    auth::{require_permission, Authenticated},
    error::ApiResult,
    response::{ApiResponse, PaginationParams},
    routes::AppState,
};

/// Build DEX routes.
pub fn router() -> Router<AppState> {
    Router::new()
        // Markets
        .route("/markets", get(list_markets))
        .route("/markets/:symbol", get(get_market))
        .route("/markets/:symbol/orderbook", get(get_orderbook))
        .route("/markets/:symbol/trades", get(get_trades))
        // Spot trading
        .route("/spot/order", post(place_order))
        .route("/spot/order/:order_id", get(get_order))
        .route("/spot/order/:order_id", delete(cancel_order))
        .route("/spot/orders", get(list_orders))
        // Perpetuals
        .route("/perps/markets", get(list_perp_markets))
        .route("/perps/positions", get(list_positions))
        .route("/perps/order", post(place_perp_order))
        // Liquidity
        .route("/liquidity/pools", get(list_pools))
        .route("/liquidity/pools/:pool_id", get(get_pool))
        .route("/liquidity/add", post(add_liquidity))
        .route("/liquidity/remove", post(remove_liquidity))
        // Account
        .route("/account/balances", get(get_balances))
        .route("/account/history", get(get_trade_history))
}

// Types
#[derive(Debug, Serialize)]
pub struct Market {
    pub symbol: String,
    pub base_asset: String,
    pub quote_asset: String,
    pub last_price: String,
    pub change_24h: String,
    pub volume_24h: String,
    pub status: String,
}

#[derive(Debug, Serialize)]
pub struct OrderbookEntry {
    pub price: String,
    pub quantity: String,
}

#[derive(Debug, Serialize)]
pub struct Orderbook {
    pub bids: Vec<OrderbookEntry>,
    pub asks: Vec<OrderbookEntry>,
    pub spread: String,
}

#[derive(Debug, Deserialize)]
pub struct PlaceOrderRequest {
    pub symbol: String,
    pub side: String,
    pub order_type: String,
    pub quantity: String,
    pub price: Option<String>,
    pub time_in_force: Option<String>,
}

#[derive(Debug, Serialize)]
pub struct Order {
    pub order_id: String,
    pub symbol: String,
    pub side: String,
    pub order_type: String,
    pub price: String,
    pub quantity: String,
    pub filled: String,
    pub status: String,
    pub created_at: String,
}

#[derive(Debug, Serialize)]
pub struct Pool {
    pub pool_id: String,
    pub name: String,
    pub token_a: String,
    pub token_b: String,
    pub reserve_a: String,
    pub reserve_b: String,
    pub tvl: String,
    pub apr: String,
}

#[derive(Debug, Deserialize)]
pub struct AddLiquidityRequest {
    pub pool_id: String,
    pub amount_a: String,
    pub amount_b: String,
    pub slippage: Option<String>,
}

// Handlers
async fn list_markets(
    State(state): State<AppState>,
    Authenticated(auth): Authenticated,
) -> ApiResult<Json<ApiResponse<Vec<Market>>>> {
    require_permission(&auth, "read")?;

    let markets = vec![
        Market {
            symbol: "ETH-USDC".to_string(),
            base_asset: "ETH".to_string(),
            quote_asset: "USDC".to_string(),
            last_price: "3000.00".to_string(),
            change_24h: "2.5".to_string(),
            volume_24h: "10000000".to_string(),
            status: "active".to_string(),
        },
    ];

    Ok(Json(ApiResponse::success(markets)))
}

async fn get_market(
    State(state): State<AppState>,
    Authenticated(auth): Authenticated,
    Path(symbol): Path<String>,
) -> ApiResult<Json<ApiResponse<Market>>> {
    require_permission(&auth, "read")?;

    let market = Market {
        symbol,
        base_asset: "ETH".to_string(),
        quote_asset: "USDC".to_string(),
        last_price: "3000.00".to_string(),
        change_24h: "2.5".to_string(),
        volume_24h: "10000000".to_string(),
        status: "active".to_string(),
    };

    Ok(Json(ApiResponse::success(market)))
}

async fn get_orderbook(
    State(state): State<AppState>,
    Authenticated(auth): Authenticated,
    Path(symbol): Path<String>,
) -> ApiResult<Json<ApiResponse<Orderbook>>> {
    require_permission(&auth, "read")?;

    let orderbook = Orderbook {
        bids: vec![OrderbookEntry { price: "2999.00".to_string(), quantity: "1.5".to_string() }],
        asks: vec![OrderbookEntry { price: "3001.00".to_string(), quantity: "2.0".to_string() }],
        spread: "2.00".to_string(),
    };

    Ok(Json(ApiResponse::success(orderbook)))
}

async fn get_trades(
    State(state): State<AppState>,
    Authenticated(auth): Authenticated,
    Path(symbol): Path<String>,
    Query(pagination): Query<PaginationParams>,
) -> ApiResult<Json<ApiResponse<Vec<serde_json::Value>>>> {
    require_permission(&auth, "read")?;

    let trades = vec![];
    let meta = pagination.to_meta(0);
    Ok(Json(ApiResponse::success_paginated(trades, meta)))
}

async fn place_order(
    State(state): State<AppState>,
    Authenticated(auth): Authenticated,
    Json(req): Json<PlaceOrderRequest>,
) -> ApiResult<Json<ApiResponse<Order>>> {
    require_permission(&auth, "write")?;

    let order = Order {
        order_id: "ord_123...".to_string(),
        symbol: req.symbol,
        side: req.side,
        order_type: req.order_type,
        price: req.price.unwrap_or_default(),
        quantity: req.quantity,
        filled: "0".to_string(),
        status: "open".to_string(),
        created_at: "2024-01-15T10:30:00Z".to_string(),
    };

    Ok(Json(ApiResponse::success(order)))
}

async fn get_order(
    State(state): State<AppState>,
    Authenticated(auth): Authenticated,
    Path(order_id): Path<String>,
) -> ApiResult<Json<ApiResponse<Order>>> {
    require_permission(&auth, "read")?;

    let order = Order {
        order_id,
        symbol: "ETH-USDC".to_string(),
        side: "buy".to_string(),
        order_type: "limit".to_string(),
        price: "3000.00".to_string(),
        quantity: "1.0".to_string(),
        filled: "0.5".to_string(),
        status: "partially_filled".to_string(),
        created_at: "2024-01-15T10:30:00Z".to_string(),
    };

    Ok(Json(ApiResponse::success(order)))
}

async fn cancel_order(
    State(state): State<AppState>,
    Authenticated(auth): Authenticated,
    Path(order_id): Path<String>,
) -> ApiResult<Json<ApiResponse<Order>>> {
    require_permission(&auth, "write")?;

    let order = Order {
        order_id,
        symbol: "ETH-USDC".to_string(),
        side: "buy".to_string(),
        order_type: "limit".to_string(),
        price: "3000.00".to_string(),
        quantity: "1.0".to_string(),
        filled: "0.0".to_string(),
        status: "cancelled".to_string(),
        created_at: "2024-01-15T10:30:00Z".to_string(),
    };

    Ok(Json(ApiResponse::success(order)))
}

async fn list_orders(
    State(state): State<AppState>,
    Authenticated(auth): Authenticated,
    Query(pagination): Query<PaginationParams>,
) -> ApiResult<Json<ApiResponse<Vec<Order>>>> {
    require_permission(&auth, "read")?;

    let orders = vec![];
    let meta = pagination.to_meta(0);
    Ok(Json(ApiResponse::success_paginated(orders, meta)))
}

async fn list_perp_markets(
    State(state): State<AppState>,
    Authenticated(auth): Authenticated,
) -> ApiResult<Json<ApiResponse<Vec<serde_json::Value>>>> {
    require_permission(&auth, "read")?;
    Ok(Json(ApiResponse::success(vec![])))
}

async fn list_positions(
    State(state): State<AppState>,
    Authenticated(auth): Authenticated,
) -> ApiResult<Json<ApiResponse<Vec<serde_json::Value>>>> {
    require_permission(&auth, "read")?;
    Ok(Json(ApiResponse::success(vec![])))
}

async fn place_perp_order(
    State(state): State<AppState>,
    Authenticated(auth): Authenticated,
    Json(req): Json<serde_json::Value>,
) -> ApiResult<Json<ApiResponse<serde_json::Value>>> {
    require_permission(&auth, "write")?;
    Ok(Json(ApiResponse::success(serde_json::json!({"order_id": "perp_123"}))))
}

async fn list_pools(
    State(state): State<AppState>,
    Authenticated(auth): Authenticated,
) -> ApiResult<Json<ApiResponse<Vec<Pool>>>> {
    require_permission(&auth, "read")?;

    let pools = vec![
        Pool {
            pool_id: "ETH-USDC".to_string(),
            name: "ETH/USDC".to_string(),
            token_a: "ETH".to_string(),
            token_b: "USDC".to_string(),
            reserve_a: "1000".to_string(),
            reserve_b: "3000000".to_string(),
            tvl: "6000000".to_string(),
            apr: "15.5".to_string(),
        },
    ];

    Ok(Json(ApiResponse::success(pools)))
}

async fn get_pool(
    State(state): State<AppState>,
    Authenticated(auth): Authenticated,
    Path(pool_id): Path<String>,
) -> ApiResult<Json<ApiResponse<Pool>>> {
    require_permission(&auth, "read")?;

    let pool = Pool {
        pool_id,
        name: "ETH/USDC".to_string(),
        token_a: "ETH".to_string(),
        token_b: "USDC".to_string(),
        reserve_a: "1000".to_string(),
        reserve_b: "3000000".to_string(),
        tvl: "6000000".to_string(),
        apr: "15.5".to_string(),
    };

    Ok(Json(ApiResponse::success(pool)))
}

async fn add_liquidity(
    State(state): State<AppState>,
    Authenticated(auth): Authenticated,
    Json(req): Json<AddLiquidityRequest>,
) -> ApiResult<Json<ApiResponse<serde_json::Value>>> {
    require_permission(&auth, "write")?;

    let result = serde_json::json!({
        "lp_tokens": "100.0",
        "share_of_pool": "0.01"
    });

    Ok(Json(ApiResponse::success(result)))
}

async fn remove_liquidity(
    State(state): State<AppState>,
    Authenticated(auth): Authenticated,
    Json(req): Json<serde_json::Value>,
) -> ApiResult<Json<ApiResponse<serde_json::Value>>> {
    require_permission(&auth, "write")?;

    let result = serde_json::json!({
        "amount_a": "1.0",
        "amount_b": "3000.0"
    });

    Ok(Json(ApiResponse::success(result)))
}

async fn get_balances(
    State(state): State<AppState>,
    Authenticated(auth): Authenticated,
) -> ApiResult<Json<ApiResponse<Vec<serde_json::Value>>>> {
    require_permission(&auth, "read")?;
    Ok(Json(ApiResponse::success(vec![])))
}

async fn get_trade_history(
    State(state): State<AppState>,
    Authenticated(auth): Authenticated,
    Query(pagination): Query<PaginationParams>,
) -> ApiResult<Json<ApiResponse<Vec<serde_json::Value>>>> {
    require_permission(&auth, "read")?;
    let meta = pagination.to_meta(0);
    Ok(Json(ApiResponse::success_paginated(vec![], meta)))
}
