use std::path::{Path, PathBuf};

use std::env;
use std::fs;
use std::str;
use glob::glob;
use regex::Regex;
use std::collections::HashMap;

#[derive(Clone, Debug)]
struct ModuleInfo {
    name: String,
    version: String,
    path: String,
}

fn check_unstable(proto_path: &PathBuf, build_unstable: bool) -> bool {
    if build_unstable {
        return true;
    }
    let proto_path_str: &str = proto_path.to_str().unwrap();

    return !(proto_path_str.contains("alpha/") || proto_path_str.contains("beta/") || proto_path_str.contains("dev/"));
}

fn find_proto_files(proto_dir: &str, build_unstable: bool) -> impl Iterator<Item = PathBuf> {
    let proto_pattern = format!("{}/**/*.proto", proto_dir);
    match glob(&proto_pattern) {
        Ok(iter) => iter
            .map(|item| item.expect("Unable to read file"))
            .filter(move |item| check_unstable(item, build_unstable))
            .map(|item| item.to_owned()),
        Err(err) => panic!(
            "Unable to read proto directory {}: {:?}",
            proto_dir,
            err
        )
    }
}

fn main() -> Result<(), Box<dyn std::error::Error>> {
    let proto_dir = "./proto/sentry_protos";
    println!("Generating protos in {}", proto_dir);

    let build_unstable = match env::var("SENTRY_PROTOS_BUILD_UNSTABLE") {
        Ok(v) => v == "1",
        Err(_) => false,
    };
    let mut build_mode = "stable";
    if build_unstable {
        build_mode = "unstable";
    }
    println!("Building {build_mode} protos");

    // collect module names to generate lib.rs
    let mut module_metadata = Vec::new();
    let mut proto_files: Vec<PathBuf> = Vec::new();
    for file in find_proto_files(proto_dir, build_unstable) {
        module_metadata.push(get_module_info(&file));
        proto_files.push(file);
    }

    // Compile rust code for all proto files.
    // You can use .out_dir("./src") to generate code into files for local inspection.
    println!("Generating proto bindings");
    tonic_build::configure()
        .emit_rerun_if_changed(false)
        .compile(&proto_files, &["./proto"])
        .unwrap();

    let mut visited: Vec<&str> = vec![];

    let mut code = String::new();
    use std::fmt::Write;
    let mut module_map = HashMap::<&str, Vec<&ModuleInfo>>::new();


    for module in module_metadata.iter() {
        module_map.entry(&module.name).and_modify(|e| {e.push(module)}).or_insert(vec![module]);
    }


    for (module_name, modules) in module_map.iter() {
        writeln!(code, "pub mod {module_name} {{").unwrap();
        for module in modules.iter() {
            if visited.iter().any(|i| i.contains(&module.path)) {
                continue;
            }
            visited.push(module.path.as_str());
            let module_version = &module.version;
            let module_path = &module.path;
            writeln!(code, "    pub mod {module_version} {{").unwrap();
            writeln!(code, "       tonic::include_proto!(\"{module_path}\");").unwrap();
            writeln!(code, "   }}").unwrap();
        }
        writeln!(code, "}}").unwrap();
        writeln!(code, "").unwrap();
    }

    // Generate lib.rs with the proto modules.
    println!("Generating src/lib.rs");
    std::fs::write(
        Path::new("./src/lib.rs"),
        code
    )
    .expect("Failed to write lib.rs");

    // Once protos are built, layer in client adapters.
    Ok(())
}

fn get_module_info(path: &PathBuf) -> ModuleInfo {
    let file = fs::read(path);
    let Ok(contents) = file else {
        panic!("Could not read {:?}", path);
    };
    let contents_str = str::from_utf8(&contents).unwrap();
    let pattern = Regex::new(r"(?m)^package\s+(?<name>[^;]+);").unwrap();
    let Some(captures) = pattern.captures(contents_str) else {
        panic!("Could not find package name in {:?}", path);
    };
    let package_name = captures["name"].to_string();
    let mut parts = package_name.split('.');

    let version = parts.nth_back(0).unwrap().to_string();
    let name = parts.nth_back(0).unwrap().to_string();

    ModuleInfo {name, version, path: package_name}
}