use rcgen::{
    CertificateParams, DistinguishedName, DnType, ExtendedKeyUsagePurpose, IsCa, KeyPair,
    KeyUsagePurpose, SanType,
};

const CA_KEY: &str = "-----BEGIN PRIVATE KEY-----
MIG2AgEAMBAGByqGSM49AgEGBSuBBAAiBIGeMIGbAgEBBDAAAAAAAAAAAAAAAAAA
AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAShZANiAAQTglHNUqyS
mMHIqtl3Mh3rl+cJvQtMoKylXcitUdz8nRWJoVl+OlEg4e/WMcY+GDXKyuKYaaYu
FjHoooGBq1ZhbcRdkYq8CfOrDmPPeSqk3O1zh743u6VpVJ8cArJw7Wc=
-----END PRIVATE KEY-----";

const CA_CHAIN: &str = "-----BEGIN PRIVATE KEY-----
MIG2AgEAMBAGByqGSM49AgEGBSuBBAAiBIGeMIGbAgEBBDAAAAAAAAAAAAAAAAAA
AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAShZANiAAQTglHNUqyS
mMHIqtl3Mh3rl+cJvQtMoKylXcitUdz8nRWJoVl+OlEg4e/WMcY+GDXKyuKYaaYu
FjHoooGBq1ZhbcRdkYq8CfOrDmPPeSqk3O1zh743u6VpVJ8cArJw7Wc=
-----END PRIVATE KEY-----
-----BEGIN CERTIFICATE-----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-----END CERTIFICATE-----
-----BEGIN CERTIFICATE-----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-----END CERTIFICATE-----
-----BEGIN CERTIFICATE-----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-----END CERTIFICATE-----";

pub const SAN: &[&str] = &[
    // 国服
    "*.dailygn.com",
    // 日服
    "production-game-api.sekai.colorfulpalette.org",
    "*.sekai.colorfulpalette.org",
    // 国际服
    "n-production-game-api.sekai-en.com",
    "*.sekai-en.com",
    // 台服 / 韩服（cdn 和 https 两个域都会出现）
    "*.bytedgame.com",
    "mk-zian-obt-cdn.bytedgame.com",
    "mk-zian-obt-https.bytedgame.com",
    "mkkorea-obt-prod01-cdn.bytedgame.com",
    "mkkorea-obt-prod01-https.bytedgame.com",
];

#[allow(unused)] // caused in re-build in build.rs
pub fn check_cert_included<'a>(target_hosts: impl Iterator<Item = &'a str>) -> bool {
    for host in target_hosts {
        if SAN.contains(&host) {
            continue;
        }
        let mut found = false;
        for included_host in SAN {
            if !included_host.starts_with("*.") {
                continue;
            }
            let without_star = &included_host[2..];
            let host_without_first = host.split_once(".");
            if let Some(parts) = host_without_first
                && parts.1 == without_star
            {
                found = true;
                break;
            }
        }
        if !found {
            return false;
        }
    }
    true
}

pub fn sign<'a>(target_hosts: impl Iterator<Item = &'a &'a str>) -> (String, String) {
    let mut target_hosts = target_hosts.peekable();

    let ca_key = KeyPair::from_pem(CA_KEY).expect("parse CA key failed");
    let first_ca_pem = first_pem_certificate(CA_CHAIN);
    let issuer = rcgen::Issuer::from_ca_cert_pem(&first_ca_pem, ca_key)
        .expect("build Issuer from CA cert + key failed");

    let mut leaf_params = CertificateParams::default();
    let mut dn = DistinguishedName::new();
    dn.push(DnType::CommonName, target_hosts.peek().unwrap().to_string());
    leaf_params.distinguished_name = dn;

    leaf_params.subject_alt_names = target_hosts
        .map(|d| SanType::DnsName((*d).try_into().unwrap()))
        .collect();

    leaf_params.key_usages = vec![
        KeyUsagePurpose::DigitalSignature,
        KeyUsagePurpose::KeyEncipherment,
    ];
    leaf_params.extended_key_usages = vec![ExtendedKeyUsagePurpose::ServerAuth];
    leaf_params.is_ca = IsCa::NoCa;
    // AKI 必须和签发者证书里的 SKI 一致，rcgen 的 Issuer 会自动从 CA 证书里取
    leaf_params.use_authority_key_identifier_extension = true;
    // 有效期落在 CA 的有效期内（2025-04-30 ~ 2040-04-28）
    leaf_params.not_before = rcgen::date_time_ymd(2025, 5, 1);
    leaf_params.not_after = rcgen::date_time_ymd(2038, 1, 1);

    let leaf_key = KeyPair::generate().expect("generate leaf key failed");
    let leaf_cert = leaf_params
        .signed_by(&leaf_key, &issuer)
        .expect("sign leaf cert failed");

    let fullchain_pem = format!("{}{}", leaf_cert.pem(), CA_CHAIN);
    let leaf_key_pem = leaf_key.serialize_pem();
    (fullchain_pem, leaf_key_pem)
}

fn first_pem_certificate(pem: &str) -> String {
    let begin = "-----BEGIN CERTIFICATE-----";
    let end = "-----END CERTIFICATE-----";
    if let (Some(s), Some(e)) = (pem.find(begin), pem.find(end)) {
        pem[s..e + end.len()].to_string()
    } else {
        panic!("no certificate found in CA chain PEM");
    }
}