use clap::{Parser, Subcommand};
use message_tools::BoxedMessage;
use std::{
    fs::OpenOptions,
    io::{BufRead, Write},
    os::unix::process::ExitStatusExt,
    process::{Command, ExitStatus},
};

const WEB_BUILD_DIR: &str = "web-build";

#[derive(Parser, Debug)]
#[command(author, version, about, long_about = None)]
struct Cli {
    #[command(subcommand)]
    command: Commands,
}

#[derive(Subcommand, Debug)]
enum Commands {
    /// Builds the website and server, including wasm files
    Build,

    /// Runs the server locally
    Start {
        /// Whether to build again or not
        #[arg(long)]
        rebuild: bool,
    },

    /// Generates new encryption keys
    GenKeys {
        /// How many keypairs to generate
        #[arg(short, long, default_value = "100")]
        number: usize,

        /// Directory to put the generated secret key files
        #[arg(short, long, default_value = ".local/secrets.json")]
        sk_out_dir: String,

        /// Directory to put the generated pubklic key pool
        #[arg(long, default_value = "target/public_keys.json")]
        pk_out_dir: String,
    },

    /// Reads fetched messages
    ReadMessages {
        /// Source file path
        #[arg(short, long, default_value = ".local/messages")]
        source: String,

        /// Where to find the secret keys for decrypting boxed messages
        #[arg(long, default_value = ".local/secrets.json")]
        sk_dir: String,

        /// Optional output file path for decoded messages
        /// Default: stdout
        #[arg(short, long)]
        out_dir: Option<String>,
    },
}

fn main() {
    let cli = Cli::parse();

    match &cli.command {
        Commands::Build => {
            println!("Executing build command...");
            build();
        }

        Commands::Start { rebuild } => {
            println!("Starting server...");
            if *rebuild {
                println!("Rebuilding web pages...");
                build();
            } // Change the current working directory of the running Rust program
            println!("Changing directory to {WEB_BUILD_DIR}...");
            let cd_result = std::env::set_current_dir(WEB_BUILD_DIR);

            // Use the existing helper to check the result
            handle_command_status(
                cd_result.map(|_| std::process::ExitStatus::from_raw(0)),
                "cd build dir",
            );

            println!("Running server executable...");
            // Now run the server executable from within the new current directory
            handle_command_status(Command::new("./server").status(), "run server");
        }
        Commands::GenKeys {
            number,
            sk_out_dir,
            pk_out_dir,
        } => {
            println!("Executing gen-keys command...");
            message_tools::gen_keys::generate_keys_to_file(pk_out_dir, sk_out_dir, *number)
                .expect("write key files");
        }
        Commands::ReadMessages {
            source,
            sk_dir,
            out_dir,
        } => {
            println!("Executing read-messages command...");
            let kps = load_kps(sk_dir);
            let msgs = {
                let ms = fetch_all_messages_from_dir(source).expect("failed to read messages");

                let mut unboxed: Vec<UnboxedMessage> = vec![];
                // for loop go brrr, its less than 1000 keys
                for m in ms {
                    if let Some(sk) =
                        fetch_sk(&kps, &m.remote_pk().expect("failed to parse pk bytes"))
                    {
                        let who = m.tag();
                        let message =
                            message_tools::unbox_message(m, sk).expect("failed to unbox message");
                        unboxed.push(UnboxedMessage { who, message });
                    } else {
                        eprintln!("No secret key found for message {m:?}");
                        continue;
                    }
                }

                unboxed
            };

            if let Some(dir) = out_dir {
                let mut f = OpenOptions::new()
                    .create(true)
                    .write(true)
                    .append(true)
                    .open(dir)
                    .expect("failed to create message output file");

                for msg in msgs {
                    writeln!(f, "{:?}", msg).expect("failed to write message");
                }
            } else {
                println!("{msgs:?}");
            }
        }
    }
}

fn fetch_sk(
    kps: &Vec<KeyPair>,
    pk: &message_tools::PublicKey,
) -> Option<message_tools::StaticSecret> {
    for kp in kps {
        if &kp.pk == pk {
            return Some(kp.sk.clone());
        }
    }

    return None;
}

#[allow(dead_code)] // struct for easy display using debug
#[derive(Debug)]
struct UnboxedMessage {
    who: String,
    message: String,
}

struct KeyPair {
    pub pk: message_tools::PublicKey,
    pub sk: message_tools::StaticSecret,
}

fn load_kps(path: impl AsRef<std::path::Path>) -> Vec<KeyPair> {
    let sks_bytes: Vec<Vec<u8>> = process_json_file(path).expect("failed to parse sk file");

    sks_bytes
        .into_iter()
        .map(|sk| {
            let arr: [u8; 32] = sk.try_into().expect("invalid secret");
            message_tools::StaticSecret::from(arr)
        })
        .map(|sk| KeyPair {
            pk: message_tools::PublicKey::from(&sk),
            sk,
        })
        .collect()
}

fn fetch_all_messages_from_dir(
    dir_path: impl AsRef<std::path::Path>,
) -> std::io::Result<Vec<BoxedMessage>> {
    let mut all_messages: Vec<BoxedMessage> = Vec::new();

    for entry in std::fs::read_dir(dir_path)? {
        let entry = entry?;
        let path = entry.path();

        if path.is_file() && path.extension().unwrap_or_default() == "json" {
            let file_messages = process_json_file(&path)?;
            all_messages.extend(file_messages);
        }
    }

    Ok(all_messages)
}

fn process_json_file<D: serde::de::DeserializeOwned>(
    file_path: impl AsRef<std::path::Path>,
) -> std::io::Result<Vec<D>> {
    let f = std::fs::OpenOptions::new()
        .read(true)
        .write(false)
        .open(file_path.as_ref())
        .expect(&format!("failed to open file at {:?}", file_path.as_ref()));

    let reader = std::io::BufReader::new(f);
    let mut ds: Vec<D> = vec![];

    for line in reader.lines() {
        let line = line.expect("failed to read line");
        let line = line.trim();

        if line.is_empty() {
            continue;
        }

        let d: D = serde_json::from_str::<D>(line).expect(&format!(
            "failed to parse message from file {:?}",
            file_path.as_ref()
        ));

        ds.push(d);
    }

    Ok(ds)
}

// A helper function to process the Result<ExitStatus, io::Error>
fn handle_command_status(status_result: std::io::Result<ExitStatus>, command_name: &str) {
    match status_result {
        Ok(exit_status) => {
            if !exit_status.success() {
                eprintln!(
                    "\nCommand '{}' failed with exit code: {:?}",
                    command_name,
                    exit_status.code()
                );
                std::process::exit(exit_status.code().unwrap_or(1));
            }
        }
        Err(e) => {
            eprintln!("\nFailed to execute command '{}': {}", command_name, e);
            std::process::exit(1); // Exit with an error code
        }
    }
}

fn build() {
    println!("Building wasm package...");
    // build the wasm package
    let status = Command::new("wasm-pack")
        .arg("build")
        .arg("--out-dir")
        .arg("../../routes/contact/pkg")
        .arg("crates/message-tools")
        .arg("--target")
        .arg("no-modules")
        .status();
    handle_command_status(status, "wasm-pack build");

    println!("Building server executable...");
    // build the server executable
    let status = Command::new("cargo")
        .arg("build")
        .arg("--release")
        .args(["-p", "server"])
        .args(["--target", "x86_64-unknown-linux-musl"])
        .status();
    handle_command_status(status, "cargo build server");

    let server_bin = "target/x86_64-unknown-linux-musl/release/server";

    println!("Creating build directory...");
    // make webpage build directory if it doesn't already exist
    let status = Command::new("mkdir").args(["-p", WEB_BUILD_DIR]).status();
    handle_command_status(status, "mkdir web-build");

    println!("Copying files...");
    // copy relevant files
    let status = Command::new("cp")
        .args(["-R", "-f", "routes"])
        .arg(format!("{WEB_BUILD_DIR}/routes"))
        .status();
    handle_command_status(status, "cp routes");

    let status = Command::new("cp")
        .arg("-f")
        .arg(server_bin)
        .arg(format!("{WEB_BUILD_DIR}"))
        .status();
    handle_command_status(status, "cp server bin");

    let pubkey_file = "target/public_keys.json";

    if !std::path::Path::new(pubkey_file).exists() {
        panic!("No public key file. Please generate keys first.");
    }

    let status = Command::new("mkdir")
        .args(["-p", &format!("{WEB_BUILD_DIR}/pubkeys")])
        .status();
    handle_command_status(status, "mkdir web-build");

    let status = Command::new("cp")
        .arg("-f")
        .arg("target/public_keys.json")
        .arg(format!("{WEB_BUILD_DIR}/pubkeys/"))
        .status();
    handle_command_status(status, "cp pubkeys");

    println!("\nBuild successful!");
}