use anyhow::{Context, Result};
use rand::RngExt;
use sqlx::PgPool;

use crate::{crypto, db};

const MIN_MASTER_PASSWORD_LEN: usize = 8;

pub async fn run(pool: &PgPool) -> Result<()> {
    println!("Initializing secrets master key...");
    println!();

    // Read password (no echo)
    let password = rpassword::prompt_password(format!(
        "Enter master password (at least {} characters): ",
        MIN_MASTER_PASSWORD_LEN
    ))
    .context("failed to read password")?;
    if password.chars().count() < MIN_MASTER_PASSWORD_LEN {
        anyhow::bail!(
            "Master password must be at least {} characters.",
            MIN_MASTER_PASSWORD_LEN
        );
    }
    let confirm = rpassword::prompt_password("Confirm master password: ")
        .context("failed to read password confirmation")?;
    if password != confirm {
        anyhow::bail!("Passwords do not match.");
    }

    // Get or create Argon2id salt
    let salt = match db::load_argon2_salt(pool).await? {
        Some(existing) => {
            println!("Found existing salt in database (not the first device).");
            existing
        }
        None => {
            println!("Generating new Argon2id salt and storing in database...");
            let mut salt = vec![0u8; 16];
            rand::rng().fill(&mut salt[..]);
            db::store_argon2_salt(pool, &salt).await?;
            salt
        }
    };

    // Derive master key
    print!("Deriving master key (Argon2id, this takes a moment)... ");
    let master_key = crypto::derive_master_key(&password, &salt)?;
    println!("done.");

    // Store in OS Keychain
    crypto::store_master_key(&master_key)?;

    // Self-test: encrypt and decrypt a canary value
    let canary = b"secrets-cli-canary";
    let enc = crypto::encrypt(&master_key, canary)?;
    let dec = crypto::decrypt(&master_key, &enc)?;
    if dec != canary {
        anyhow::bail!("Self-test failed: encryption roundtrip mismatch");
    }

    println!();
    println!("Master key stored in OS Keychain.");
    println!("You can now use `secrets add` / `secrets search` commands.");
    println!();
    println!("IMPORTANT: Remember your master password — it is not stored anywhere.");
    println!("           On a new device, run `secrets init` with the same password.");

    Ok(())
}