//! Implementation module
//!
//! **File:** `build.rs`
//! **Author:** Kevin Thomas
//! **Date:** 2025
//!
//! MIT License
//!
//! Copyright (c) 2025 Kevin Thomas
//!
//! Permission is hereby granted, free of charge, to any person obtaining a copy
//! of this software and associated documentation files (the "Software"), to deal
//! in the Software without restriction, including without limitation the rights
//! to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
//! copies of the Software, and to permit persons to whom the Software is
//! furnished to do so, subject to the following conditions:
//!
//! The above copyright notice and this permission notice shall be included in
//! all copies or substantial portions of the Software.
//!
//! THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
//! IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
//! FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
//! AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
//! LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
//! OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
//! SOFTWARE.

// Import regex::Regex
use regex::Regex;
// Import dependencies from std::fs
use std::fs::{File, read_to_string};
// Import std::io::Write
use std::io::Write;
// Import std::path::PathBuf
use std::path::PathBuf;

/// The main entry point.
fn main() {
    let out = PathBuf::from(std::env::var_os("OUT_DIR").unwrap());
    let contents = read_to_string(".pico-rs")
        .unwrap_or_default()
        .trim()
        .to_lowercase();
    let target = setup_target(&contents, &out);
    update_cargo_config(&target);
    write_riscv(&out);
    print_cfgs(&out);
}

/// Executes the setup target operation.
///
/// # Arguments
///
/// * `c` - Command byte.
/// * `out` - The `out` parameter.
///
/// # Returns
///
/// A value of type `String`.
fn setup_target(c: &str, out: &PathBuf) -> String {
    if c == "rp2040" {
        write_rp2040(out);
        return "thumbv6m-none-eabi".to_string();
    }
    write_rp2350(out);
    if c.contains("riscv") {
        "riscv32imac-unknown-none-elf".to_string()
    } else {
        "thumbv8m.main-none-eabihf".to_string()
    }
}

/// Executes the write rp2040 operation.
///
/// # Arguments
///
/// * `out` - The `out` parameter.
fn write_rp2040(out: &PathBuf) {
    File::create(out.join("memory.x"))
        .unwrap()
        .write_all(include_bytes!("rp2040.x"))
        .unwrap();
    println!("cargo::rustc-cfg=rp2040");
    println!("cargo:rerun-if-changed=rp2040.x");
}

/// Executes the write rp2350 operation.
///
/// # Arguments
///
/// * `out` - The `out` parameter.
fn write_rp2350(out: &PathBuf) {
    File::create(out.join("memory.x"))
        .unwrap()
        .write_all(include_bytes!("rp2350.x"))
        .unwrap();
    println!("cargo::rustc-cfg=rp2350");
    println!("cargo:rerun-if-changed=rp2350.x");
}

/// Executes the update cargo config operation.
///
/// # Arguments
///
/// * `target` - The `target` parameter.
fn update_cargo_config(target: &str) {
    let re = Regex::new(r"target = .*").unwrap();
    let result = re.replace(
        include_str!(".cargo/config.toml"),
        format!("target = \"{}\"", target),
    );
    File::create(".cargo/config.toml")
        .unwrap()
        .write_all(result.as_bytes())
        .unwrap();
}

/// Executes the write riscv operation.
///
/// # Arguments
///
/// * `out` - The `out` parameter.
fn write_riscv(out: &PathBuf) {
    File::create(out.join("rp2350_riscv.x"))
        .unwrap()
        .write_all(include_bytes!("rp2350_riscv.x"))
        .unwrap();
}

/// Executes the print cfgs operation.
///
/// # Arguments
///
/// * `out` - The `out` parameter.
fn print_cfgs(out: &PathBuf) {
    println!("cargo::rustc-check-cfg=cfg(rp2040)");
    println!("cargo::rustc-check-cfg=cfg(rp2350)");
    println!("cargo:rustc-link-search={}", out.display());
    println!("cargo:rerun-if-changed=.pico-rs");
    println!("cargo:rerun-if-changed=rp2350_riscv.x");
    println!("cargo:rerun-if-changed=build.rs");
}