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// Copyright 2015-2019 Capital One Services, LLC
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

//! # waxosuit-guest
//!
//! The `waxosuit-guest` library provides WebAssembly module developers with access to the
//! Waxosuit host runtime. Each guest module has a single call handler, declared with the
//!  `call_handler!` macro. Inside this call handler, the guest
//! module should check the operation of the delivered message and handle it accordingly,
//! returning any binary payload in response. It is the responsibility of the guest module to ensure
//! that the capability provider will be able to understand whichever messages it sends.
//!
//! # Example
//! ```
//! extern crate waxosuit_guest as guest;
//!
//! use guest::prelude::*;
//!
//! call_handler!(handle_call);
//!
//! pub fn handle_call(ctx: &CapabilitiesContext, operation: &str, msg: &[u8]) -> CallResult {
//!     match operation {
//!         http::OP_HANDLE_REQUEST => hello_world(ctx, msg),
//!         core::OP_HEALTH_REQUEST => Ok(vec![]),
//!         _ => Err("bad dispatch".into()),
//!     }     
//! }
//!
//! fn hello_world(
//!    _ctx: &CapabilitiesContext,
//!    _msg: &[u8]) -> CallResult {
//!     Ok(vec![])
//! }
//! ```

pub extern crate prost;
pub extern crate wapc_guest as wapc;
use crate::kv::KeyValueStore;
use crate::msg::MessageBroker;
use crate::raw::RawCapability;
use wapc::prelude::*;
use wapc_guest::console_log;

/// Utility function to easily convert a prost Message into a byte vector
pub fn protobytes(msg: impl prost::Message) -> Result<Vec<u8>> {
    let mut buf = Vec::new();
    msg.encode(&mut buf)?;
    Ok(buf)
}

#[macro_export]
macro_rules! call_handler {
    ($user_handler:ident) => {
        use $crate::wapc::prelude::*;

        wapc_handler!(handle_wapc);
        fn handle_wapc(operation: &str, msg: &[u8]) -> CallResult {
            let ctx = $crate::CapabilitiesContext::new();
            $user_handler(&ctx, &operation, msg)
        }
    };
}

/// The capabilities context is the gateway through which all guest modules communicate with a host runtime. A reference
/// to a capabilities context is passed to the call handler defined by the guest module. Individual capabilities are separated
/// through function calls for each capability provider, including any bound opaque `raw` providers.
pub struct CapabilitiesContext {
    kv: KeyValueStore,
    msg: MessageBroker,
    raw: RawCapability,
}

impl Default for CapabilitiesContext {
    fn default() -> CapabilitiesContext {
        CapabilitiesContext {
            kv: KeyValueStore::new(),
            msg: MessageBroker::new(),
            raw: RawCapability::new(),
        }
    }
}

impl CapabilitiesContext {
    pub fn new() -> CapabilitiesContext {
        Self::default()
    }

    pub fn kv(&self) -> &KeyValueStore {
        &self.kv
    }

    pub fn msg(&self) -> &MessageBroker {
        &self.msg
    }

    pub fn raw(&self) -> &RawCapability {
        &self.raw
    }

    pub fn log(&self, msg: &str) {
        console_log(msg);
    }
}

pub mod kv;
pub mod msg;
pub mod prelude;
pub mod raw;