// This Source Code Form is subject to the terms of the Mozilla Public
// License, version 2.0. If a copy of the MPL was not distributed with this
// file, You can obtain one at http://mozilla.org/MPL/2.0/.

#include <cstdlib>
#include <cstdint>
#include <cstring>
#include <ctime>
#include <string_view>
#include <memory>
#include <numeric>
#include <fmt/core.h>
#include <gpgme.h>
#include <weechat/weechat-plugin.h>

#include "plugin.hh"
#include "pgp.hh"

std::string format_key(weechat::xmpp::pgp &pgp, std::string_view keyid)
{
    gpgme_key_t key = nullptr;
    gpgme_error_t err = gpgme_get_key(pgp.gpgme, keyid.data(), &key, false);
    if (err) {
        return fmt::format("{} (none)", keyid);
    }
    std::string result(keyid);
    result += '{';
    {
        std::string keyids;
        for (auto subkey = key->subkeys; subkey; subkey = subkey->next)
        {
            if (!keyids.empty()) keyids += ", ";
            std::string keyid(subkey->keyid);
            if (keyid.length() > 8) keyid = keyid.substr(keyid.length()-8, 8);
            keyids += keyid;
        }
        result += keyids;
    }
    result += "}[";
    {
        std::string userids;
        for (auto uid = key->uids; uid; uid = uid->next)
        {
            if (!userids.empty()) userids += ", ";
            userids += fmt::format("{} ({})", uid->name, uid->email);
        }
        result += userids;
    }
    result += ']';
    return result;
}

#define PGP_MESSAGE_HEADER "-----BEGIN PGP MESSAGE-----\r\n"
#define PGP_MESSAGE_FOOTER "\r\n-----END PGP MESSAGE-----"
#define PGP_SIGNATURE_HEADER "-----BEGIN PGP SIGNATURE-----\r\n"
#define PGP_SIGNATURE_FOOTER "\r\n-----END PGP SIGNATURE-----"

const char *weechat::xmpp::PGP_ADVICE = "[PGP encrypted message (XEP-0027)]";

weechat::xmpp::pgp::pgp()
{
    gpgme_error_t err;
  //gpgme_data_t keydata;

    gpgme_check_version(NULL);

    err = gpgme_new(&this->gpgme);
    if (err) {
        weechat_printf(nullptr, "gpg (error): %s - %s",
                gpgme_strsource(err), gpgme_strerror(err));
        throw nullptr;
    }
    gpgme_set_armor(this->gpgme, true);

  //err = gpgme_data_new_from_file(&keydata, pub, true);
  //if (err) {
  //    return;
  //}

  //err = gpgme_op_import(this->gpgme, keydata);
  //if (err) {
  //    return;
  //}

  //gpgme_import_result_t impRes = gpgme_op_import_result(this->gpgme);
  //weechat_printf(nullptr, "(gpg) imported %d keys", impRes->imported);

  //err = gpgme_data_new_from_file(&keydata, sec, true);
  //if (err) {
  //    return;
  //}

  //err = gpgme_op_import(this->gpgme, keydata);
  //if (err) {
  //    return;
  //}

  //impRes = gpgme_op_import_result(this->gpgme);
  //weechat_printf(nullptr, "(gpg) imported %d secret keys", impRes->imported);
}

weechat::xmpp::pgp::~pgp()
{
    gpgme_release(this->gpgme);
}

char *weechat::xmpp::pgp::encrypt(struct t_gui_buffer *buffer, const char *source, std::vector<std::string>&& targets, const char *message)
{
    std::string encrypted;
    gpgme_key_t keys[3] = {NULL,NULL,NULL};
    char *           result = NULL;

    int ret;
    gpgme_error_t err;
    gpgme_data_t in, out;

    /* Initialize input buffer. */
    err = gpgme_data_new_from_mem(&in, message, strlen(message), false);
    if (err) {
        goto encrypt_finish;
    }

    /* Initialize output buffer. */
    err = gpgme_data_new(&out);
    if (err) {
        goto encrypt_finish;
    }

    /* Encrypt data. */
    for (const std::string& target : targets)
    {
        err = gpgme_get_key(this->gpgme, target.data(), &keys[0], false);
        if (err) {
            goto encrypt_finish;
        }
    }
    err = gpgme_get_key(this->gpgme, source, &keys[1], false);
    if (err) {
        goto encrypt_finish;
    }
    err = gpgme_op_encrypt(this->gpgme, keys, GPGME_ENCRYPT_ALWAYS_TRUST, in, out);
    if (err) {
        goto encrypt_finish;
    }
    if (gpgme_encrypt_result_t enc_result = gpgme_op_encrypt_result(this->gpgme);
            enc_result->invalid_recipients)
    {
        goto encrypt_finish;
    }
    gpgme_data_seek(out, 0, SEEK_SET);
    char data[512 + 1];
    while ((ret = gpgme_data_read(out, data, 512)) > 0)
    {
        encrypted += std::string_view(data, ret);
    }

    gpgme_data_release(in);
    gpgme_data_release(out);

    result = strndup(encrypted.data() + strlen(PGP_MESSAGE_HEADER),
                     encrypted.size() - strlen(PGP_MESSAGE_HEADER) - strlen(PGP_MESSAGE_FOOTER));
encrypt_finish:
    if (err) {
        weechat_printf(buffer, "[PGP]\t%s - %s",
                gpgme_strsource(err), gpgme_strerror(err));
    }
    return result;
}

//"hQIMAzlgcSFDGLKEAQ//cGG3DFughC5xBF7xeXz1RdayOfhBAPfoZIq62MVuSnfS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\npw==\n=euIB"
char *weechat::xmpp::pgp::decrypt(struct t_gui_buffer *buffer, const char *ciphertext)
{
    std::string decrypted;
    std::unique_ptr<char> buf;
    size_t buf_len = 0;
    char * result = NULL;

    int ret;

    buf_len = strlen(PGP_MESSAGE_HEADER) + strlen(ciphertext) + strlen(PGP_MESSAGE_FOOTER) + 1;
    buf = std::unique_ptr<char>(new char[buf_len]);
    buf_len = snprintf(&*buf, buf_len, PGP_MESSAGE_HEADER "%s" PGP_MESSAGE_FOOTER, ciphertext);

    std::string keyids;
    gpgme_error_t err;
    gpgme_data_t in, out;

    /* Initialize input buffer. */
    err = gpgme_data_new_from_mem(&in, &*buf, buf_len, false);
    if (err) {
        goto decrypt_finish;
    }

    /* Initialize output buffer. */
    err = gpgme_data_new(&out);
    if (err) {
        goto decrypt_finish;
    }

    /* Decrypt data. */
    err = gpgme_op_decrypt(this->gpgme, in, out);
    if (gpgme_decrypt_result_t dec_result = gpgme_op_decrypt_result(this->gpgme);
            dec_result)
    {
        for (auto recip = dec_result->recipients; recip; recip = recip->next)
        {
            if (!keyids.empty()) keyids += ", ";
            keyids += format_key(*this, recip->keyid);
        }
        if (dec_result->unsupported_algorithm)
        {
            goto decrypt_finish;
        }
    }
    if (err) {
        goto decrypt_finish;
    }
    gpgme_data_seek(out, 0, SEEK_SET);
    char data[512 + 1];
    while ((ret = gpgme_data_read(out, data, 512)) > 0)
    {
        decrypted += std::string_view(data, ret);
    }

    gpgme_data_release(in);
    gpgme_data_release(out);

    result = strndup(decrypted.data(), decrypted.size());
decrypt_finish:
    if (err) {
        weechat_printf(buffer, "[PGP]\t%s - %s (%s)",
                gpgme_strsource(err), gpgme_strerror(err), keyids.data());
    }
    return result;
}

char *weechat::xmpp::pgp::verify(struct t_gui_buffer *buffer, const char *certificate)
{
    std::unique_ptr<char> buf;
    size_t buf_len = 0;
    char * result = NULL;

    buf_len = strlen(PGP_SIGNATURE_HEADER) + strlen(certificate) + strlen(PGP_SIGNATURE_FOOTER) + 1;
    buf = std::unique_ptr<char>(new char[buf_len]);
    buf_len = snprintf(&*buf, buf_len, PGP_SIGNATURE_HEADER "%s" PGP_SIGNATURE_FOOTER, certificate);

    gpgme_verify_result_t vrf_result;
    gpgme_error_t err;
    gpgme_data_t in, out;
    gpgme_key_t key;

    /* Initialize input buffer. */
    err = gpgme_data_new_from_mem(&in, &*buf, buf_len, false);
    if (err) {
        goto verify_finish;
    }

    /* Initialize output buffer. */
    err = gpgme_data_new(&out);
    if (err) {
        goto verify_finish;
    }

    /* Verify data. */
    err = gpgme_op_verify(this->gpgme, in, out, nullptr);
    if (err) {
        goto verify_finish;
    }
    if (vrf_result = gpgme_op_verify_result(this->gpgme);
            !(vrf_result->signatures->summary & GPGME_SIGSUM_VALID))
    {
      //goto verify_finish;
    }

    result = strdup(vrf_result->signatures->fpr);

    err = gpgme_get_key(this->gpgme, result, &key, false);
    if (err) {
        const char *keyids[2] = { result, nullptr };
        err = gpgme_op_receive_keys(this->gpgme, keyids);
    }

verify_finish:
    if (err) {
        weechat_printf(buffer, "[PGP]\t%s - %s",
                gpgme_strsource(err), gpgme_strerror(err));
    }
    return result;
}

char *weechat::xmpp::pgp::sign(struct t_gui_buffer *buffer, const char *source, const char *message)
{
    std::string signature;
    char *           result = NULL;
    int ret;

    gpgme_error_t err;
    gpgme_data_t in, out;
    gpgme_key_t key;

    /* Initialize input buffer. */
    err = gpgme_data_new_from_mem(&in, (char *)message, strlen(message), false);
    if (err) {
        goto sign_finish;
    }

    /* Initialize output buffer. */
    err = gpgme_data_new(&out);
    if (err) {
        goto sign_finish;
    }

    /* Include signature within key. */
    {
        gpgme_keylist_mode_t kmode = gpgme_get_keylist_mode(this->gpgme);
        kmode |= GPGME_KEYLIST_MODE_LOCATE;
        kmode |= GPGME_KEYLIST_MODE_SIGS;
        err = gpgme_set_keylist_mode(this->gpgme, kmode);
    }
    if (err) {
        goto sign_finish;
    }

    err = gpgme_get_key(this->gpgme, source, &key, false);
    if (err) {
        weechat_printf(nullptr, "(gpg) get key fail for %s", source);
        goto sign_finish;
    }
    err = gpgme_signers_add(this->gpgme, key);
    if (err) {
        weechat_printf(nullptr, "(gpg) add key fail for %s", source);
        goto sign_finish;
    }

    /* Sign data. */
    err = gpgme_op_sign(this->gpgme, in, out, GPGME_SIG_MODE_DETACH);
    if (err) {
        weechat_printf(nullptr, "(gpg) sign fail for %s", source);
        goto sign_finish;
    }
    if (gpgme_sign_result_t sgn_result = gpgme_op_sign_result(this->gpgme);
            !sgn_result->signatures)
    {
        weechat_printf(nullptr, "(gpg) signature fail for %s", source);
    }
    gpgme_data_seek(out, 0, SEEK_SET);
    char data[512 + 1];
    while ((ret = gpgme_data_read(out, data, 512)) > 0)
    {
        signature += std::string_view(data, ret);
    }

    gpgme_data_release(in);
    gpgme_data_release(out);

    result = strndup(signature.data() + strlen(PGP_SIGNATURE_HEADER),
                     signature.size() - strlen(PGP_SIGNATURE_HEADER) - strlen(PGP_SIGNATURE_FOOTER));
sign_finish:
    if (err) {
        weechat_printf(buffer, "[PGP]\t%s - %s",
                gpgme_strsource(err), gpgme_strerror(err));
    }
    return result;
}