//! lnd config bootstrap helper.

use anyhow::{Context, Result};
use base64::Engine;
use serde::{Deserialize, Serialize};
use std::path::PathBuf;
use tokio::fs;

use crate::update::host_sudo;

pub const DEFAULT_DATA_DIR: &str = "/var/lib/archipelago/lnd";
pub const DEFAULT_CONF_PATH: &str = "/var/lib/archipelago/lnd/lnd.conf";
pub const WALLET_PASSWORD: &str = "hellohello";

#[derive(Debug, Clone)]
pub struct EnsurePaths {
    pub data_dir: PathBuf,
    pub conf_path: PathBuf,
}

impl Default for EnsurePaths {
    fn default() -> Self {
        Self {
            data_dir: PathBuf::from(DEFAULT_DATA_DIR),
            conf_path: PathBuf::from(DEFAULT_CONF_PATH),
        }
    }
}

#[derive(Debug, Clone, Copy, PartialEq, Eq)]
pub enum EnsureOutcome {
    Written,
    Unchanged,
}

pub async fn ensure_config(paths: &EnsurePaths, rpc_pass: &str) -> Result<EnsureOutcome> {
    fs::create_dir_all(&paths.data_dir)
        .await
        .with_context(|| format!("creating {}", paths.data_dir.display()))?;

    if paths.conf_path.exists() {
        let existing = fs::read_to_string(&paths.conf_path)
            .await
            .with_context(|| format!("reading {}", paths.conf_path.display()))?;
        if has_required_lnd_flags(&existing) {
            return Ok(EnsureOutcome::Unchanged);
        }
    }

    let conf = format!(
        "debuglevel=info\n\
maxpendingchannels=10\n\
alias=Archipelago Node\n\
color=#f7931a\n\
listen=0.0.0.0:9735\n\
rpclisten=0.0.0.0:10009\n\
restlisten=0.0.0.0:8080\n\
bitcoin.active=true\n\
bitcoin.mainnet=true\n\
bitcoin.node=bitcoind\n\
bitcoind.rpchost=bitcoin-knots:8332\n\
bitcoind.rpcuser=archipelago\n\
bitcoind.rpcpass={}\n\
bitcoind.rpcpolling=true\n\
bitcoind.estimatemode=ECONOMICAL\n",
        rpc_pass
    );

    write_config_atomically(paths, &conf).await?;

    Ok(EnsureOutcome::Written)
}

pub async fn ensure_wallet_initialized() -> Result<()> {
    let admin_macaroon = "/var/lib/archipelago/lnd/data/chain/bitcoin/mainnet/admin.macaroon";
    let wallet_db = "/var/lib/archipelago/lnd/data/chain/bitcoin/mainnet/wallet.db";
    if file_exists_as_root(wallet_db).await {
        if file_exists_as_root(admin_macaroon).await && lnd_getinfo_ready(admin_macaroon).await {
            return Ok(());
        }
        unlock_existing_wallet().await?;
        wait_for_admin_macaroon(admin_macaroon).await?;
        return Ok(());
    }

    init_wallet_via_rest().await?;
    wait_for_admin_macaroon(admin_macaroon).await
}

async fn file_exists_as_root(path: &str) -> bool {
    if std::path::Path::new(path).exists() {
        return true;
    }
    tokio::process::Command::new("sudo")
        .args(["test", "-f", path])
        .status()
        .await
        .map(|status| status.success())
        .unwrap_or(false)
}

async fn read_file_as_root(path: &str) -> Result<Vec<u8>> {
    match fs::read(path).await {
        Ok(bytes) => Ok(bytes),
        Err(direct_err) => {
            let out = tokio::process::Command::new("sudo")
                .args(["cat", path])
                .output()
                .await
                .with_context(|| format!("reading {path} via sudo"))?;
            if out.status.success() {
                Ok(out.stdout)
            } else {
                anyhow::bail!(
                    "reading {path} failed (direct: {direct_err}; sudo: {})",
                    String::from_utf8_lossy(&out.stderr).trim()
                )
            }
        }
    }
}

async fn unlock_existing_wallet() -> Result<()> {
    let mut last_err = None;
    for _ in 0..60 {
        let mut cmd = tokio::process::Command::new("podman");
        cmd.args(["exec", "-i", "lnd", "lncli", "unlock", "--stdin"]);
        cmd.stdin(std::process::Stdio::piped());
        cmd.stdout(std::process::Stdio::piped());
        cmd.stderr(std::process::Stdio::piped());

        let mut child = cmd.spawn().context("spawning lncli wallet unlock")?;
        if let Some(mut stdin) = child.stdin.take() {
            use tokio::io::AsyncWriteExt;
            stdin
                .write_all(format!("{}\n", WALLET_PASSWORD).as_bytes())
                .await
                .context("writing lncli password")?;
        }
        let out = child
            .wait_with_output()
            .await
            .context("waiting for lncli")?;
        if out.status.success() {
            return Ok(());
        }
        let stderr = String::from_utf8_lossy(&out.stderr);
        let stdout = String::from_utf8_lossy(&out.stdout);
        let msg = format!("{stderr}{stdout}");
        if msg.contains("wallet already unlocked") || msg.contains("already unlocked") {
            return Ok(());
        }
        last_err = Some(msg);
        tokio::time::sleep(std::time::Duration::from_secs(1)).await;
    }
    anyhow::bail!(
        "lncli wallet unlock failed: {}",
        last_err.unwrap_or_else(|| "unknown error".to_string())
    )
}

#[derive(Debug, Deserialize)]
struct GenSeedResponse {
    cipher_seed_mnemonic: Vec<String>,
}

#[derive(Debug)]
enum UnlockerResponse<T> {
    Value(T),
    WalletAlreadyExists,
}

#[derive(Debug, Serialize)]
struct InitWalletRequest {
    wallet_password: String,
    cipher_seed_mnemonic: Vec<String>,
}

async fn init_wallet_via_rest() -> Result<()> {
    let client = reqwest::Client::builder()
        .timeout(std::time::Duration::from_secs(20))
        .danger_accept_invalid_certs(true)
        .build()
        .context("building LND REST client")?;

    let seed: GenSeedResponse = match get_lnd_unlocker_json(&client, "/v1/genseed")
        .await
        .context("generating LND wallet seed")?
    {
        UnlockerResponse::Value(seed) => seed,
        UnlockerResponse::WalletAlreadyExists => {
            unlock_existing_wallet().await?;
            return Ok(());
        }
    };
    if seed.cipher_seed_mnemonic.is_empty() {
        anyhow::bail!("LND genseed returned no seed words");
    }

    let wallet_password = base64::engine::general_purpose::STANDARD.encode(WALLET_PASSWORD);
    let req = InitWalletRequest {
        wallet_password,
        cipher_seed_mnemonic: seed.cipher_seed_mnemonic,
    };
    match post_lnd_unlocker_json::<serde_json::Value>(
        &client,
        "/v1/initwallet",
        serde_json::to_value(req)?,
    )
    .await
    .context("initializing LND wallet")?
    {
        UnlockerResponse::Value(_) => {}
        UnlockerResponse::WalletAlreadyExists => unlock_existing_wallet().await?,
    }

    Ok(())
}

async fn get_lnd_unlocker_json<T: for<'de> Deserialize<'de>>(
    client: &reqwest::Client,
    path: &str,
) -> Result<UnlockerResponse<T>> {
    let url = format!("https://127.0.0.1:8080{path}");
    let mut last_err = None;
    for _ in 0..60 {
        match client.get(&url).send().await {
            Ok(resp) => match decode_lnd_unlocker_response(resp, path).await {
                Ok(value) => return Ok(value),
                Err(e) => last_err = Some(e.to_string()),
            },
            Err(e) => last_err = Some(e.to_string()),
        }
        tokio::time::sleep(std::time::Duration::from_secs(1)).await;
    }
    anyhow::bail!(
        "LND REST {path} unavailable: {}",
        last_err.unwrap_or_else(|| "unknown error".to_string())
    )
}

async fn post_lnd_unlocker_json<T: for<'de> Deserialize<'de>>(
    client: &reqwest::Client,
    path: &str,
    body: serde_json::Value,
) -> Result<UnlockerResponse<T>> {
    let url = format!("https://127.0.0.1:8080{path}");
    let mut last_err = None;
    for _ in 0..60 {
        match client.post(&url).json(&body).send().await {
            Ok(resp) => match decode_lnd_unlocker_response(resp, path).await {
                Ok(value) => return Ok(value),
                Err(e) => last_err = Some(e.to_string()),
            },
            Err(e) => last_err = Some(e.to_string()),
        }
        tokio::time::sleep(std::time::Duration::from_secs(1)).await;
    }
    anyhow::bail!(
        "LND REST {path} unavailable: {}",
        last_err.unwrap_or_else(|| "unknown error".to_string())
    )
}

async fn decode_lnd_unlocker_response<T: for<'de> Deserialize<'de>>(
    resp: reqwest::Response,
    path: &str,
) -> Result<UnlockerResponse<T>> {
    let status = resp.status();
    let text = resp.text().await.unwrap_or_default();
    if status.is_success() {
        let value = serde_json::from_str(&text)
            .with_context(|| format!("parsing LND REST response from {path}"))?;
        return Ok(UnlockerResponse::Value(value));
    }
    if text.contains("wallet already exists") {
        return Ok(UnlockerResponse::WalletAlreadyExists);
    }
    anyhow::bail!("LND REST {path} returned {status}: {text}")
}

async fn lnd_getinfo_ready(admin_macaroon: &str) -> bool {
    let Ok(macaroon) = read_file_as_root(admin_macaroon).await else {
        return false;
    };
    let Ok(client) = reqwest::Client::builder()
        .timeout(std::time::Duration::from_secs(5))
        .danger_accept_invalid_certs(true)
        .build()
    else {
        return false;
    };
    client
        .get("https://127.0.0.1:8080/v1/getinfo")
        .header("Grpc-Metadata-macaroon", hex::encode(macaroon))
        .send()
        .await
        .map(|resp| resp.status().is_success())
        .unwrap_or(false)
}

async fn wait_for_admin_macaroon(admin_macaroon: &str) -> Result<()> {
    for _ in 0..60 {
        if file_exists_as_root(admin_macaroon).await {
            return Ok(());
        }
        tokio::time::sleep(std::time::Duration::from_secs(1)).await;
    }
    anyhow::bail!("LND admin macaroon not created after wallet init")
}

async fn write_config_atomically(paths: &EnsurePaths, conf: &str) -> Result<()> {
    let tmp = paths.conf_path.with_extension("tmp");
    match fs::write(&tmp, conf).await {
        Ok(()) => {
            fs::rename(&tmp, &paths.conf_path).await.with_context(|| {
                format!(
                    "renaming {} -> {}",
                    tmp.display(),
                    paths.conf_path.display()
                )
            })?;
            Ok(())
        }
        Err(e) if e.kind() == std::io::ErrorKind::PermissionDenied => {
            let script = format!(
                "set -eu\ncat > '{}' <<'LNDCONF'\n{}LNDCONF\n",
                shell_quote(&paths.conf_path.to_string_lossy()),
                conf
            );
            let status = host_sudo(&["sh", "-lc", &script])
                .await
                .context("writing lnd.conf via sudo")?;
            if !status.success() {
                anyhow::bail!("writing lnd.conf via sudo exited with {status}");
            }
            Ok(())
        }
        Err(e) => Err(e).with_context(|| format!("writing tmp {}", tmp.display())),
    }
}

fn shell_quote(s: &str) -> String {
    s.replace('\'', "'\\''")
}

fn has_required_lnd_flags(conf: &str) -> bool {
    [
        "bitcoin.active=true",
        "bitcoin.mainnet=true",
        "bitcoin.node=bitcoind",
        "bitcoind.rpchost=bitcoin-knots:8332",
    ]
    .iter()
    .all(|needle| conf.lines().any(|line| line.trim() == *needle))
}

#[cfg(test)]
mod tests {
    use super::*;

    #[tokio::test]
    async fn ensure_config_writes_required_bitcoin_network_flags() {
        let tmp = tempfile::TempDir::new().unwrap();
        let paths = EnsurePaths {
            data_dir: tmp.path().join("lnd"),
            conf_path: tmp.path().join("lnd/lnd.conf"),
        };

        let out = ensure_config(&paths, "secret").await.unwrap();
        assert_eq!(out, EnsureOutcome::Written);
        let conf = fs::read_to_string(&paths.conf_path).await.unwrap();
        assert!(conf.contains("bitcoin.active=true"));
        assert!(conf.contains("bitcoin.mainnet=true"));
        assert!(conf.contains("bitcoin.node=bitcoind"));
        assert!(conf.contains("bitcoind.rpchost=bitcoin-knots:8332"));
        assert!(conf.contains("bitcoind.rpcpass=secret"));
    }

    #[tokio::test]
    async fn ensure_config_is_idempotent() {
        let tmp = tempfile::TempDir::new().unwrap();
        let paths = EnsurePaths {
            data_dir: tmp.path().join("lnd"),
            conf_path: tmp.path().join("lnd/lnd.conf"),
        };

        assert_eq!(
            ensure_config(&paths, "first").await.unwrap(),
            EnsureOutcome::Written
        );
        assert_eq!(
            ensure_config(&paths, "second").await.unwrap(),
            EnsureOutcome::Unchanged
        );
        let conf = fs::read_to_string(&paths.conf_path).await.unwrap();
        assert!(conf.contains("bitcoind.rpcpass=first"));
    }

    #[tokio::test]
    async fn ensure_config_repairs_incomplete_existing_config() {
        let tmp = tempfile::TempDir::new().unwrap();
        let paths = EnsurePaths {
            data_dir: tmp.path().join("lnd"),
            conf_path: tmp.path().join("lnd/lnd.conf"),
        };
        fs::create_dir_all(&paths.data_dir).await.unwrap();
        fs::write(&paths.conf_path, "debuglevel=info\n")
            .await
            .unwrap();

        assert_eq!(
            ensure_config(&paths, "repaired").await.unwrap(),
            EnsureOutcome::Written
        );
        let conf = fs::read_to_string(&paths.conf_path).await.unwrap();
        assert!(conf.contains("bitcoin.mainnet=true"));
        assert!(conf.contains("bitcoind.rpcpass=repaired"));
    }

    #[test]
    fn wallet_password_is_valid_for_lncli() {
        assert!(WALLET_PASSWORD.len() > 8);
    }
}