/*
 * Copyright 2020 Fluence Labs Limited
 *
 * 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.
 */

use crate::instructions_generator::WITGenerator;
use crate::default_export_api_config::*;

pub use fluence_sdk_wit::FCEAst;
use wasmer_wit::ast::Interfaces;

// TODO: add error handling
/// Parse generated by rust-sdk AST types, generate instructions and embed them to Wasm file.
pub fn embed_wit(path: std::path::PathBuf) {
    let wasm_module = walrus::ModuleConfig::new()
        .parse_file(path.clone())
        .unwrap();
    let ast_set = wasm_ast_extractor(&wasm_module);
    let interfaces = generate_interfaces(&ast_set);

    let mut wasm_module = wit_parser::embed_wit(wasm_module, &interfaces);
    wasm_module.emit_wasm_file(path).unwrap();
}

/// Extract all custom AST types previously embedded by rust-sdk from compiled binary.
fn wasm_ast_extractor(wasm_module: &walrus::Module) -> Vec<fluence_sdk_wit::FCEAst> {
    let mut extracted_ast = Vec::new();

    // consider only sections name of that starts with GENERATED_SECTION_PREFIX
    for custom_module in wasm_module.customs.iter().filter(|(_, section)| {
        section
            .name()
            .starts_with(fluence_sdk_wit::GENERATED_SECTION_PREFIX)
    }) {
        let default_ids = walrus::IdsToIndices::default();
        let raw_data = custom_module.1.data(&default_ids);
        let decoded_json: fluence_sdk_wit::FCEAst = serde_json::from_slice(&raw_data).unwrap();
        extracted_ast.push(decoded_json);
    }

    extracted_ast
}

fn generate_interfaces(ast_set: &[FCEAst]) -> Interfaces<'_> {
    let mut interfaces = Interfaces::default();
    generate_default_export_api(&mut interfaces);

    for ast in ast_set {
        ast.generate_wit(&mut interfaces);
    }

    interfaces
}

fn generate_default_export_api(interfaces: &mut Interfaces) {
    ALLOCATE_FUNC.update_interfaces(interfaces);
    DEALLOCATE_FUNC.update_interfaces(interfaces);
    SET_RESULT_SIZE_FUNC.update_interfaces(interfaces);
    SET_RESULT_PTR_FUNC.update_interfaces(interfaces);
    GET_RESULT_SIZE_FUNC.update_interfaces(interfaces);
    GET_RESULT_PTR_FUNC.update_interfaces(interfaces);
}