/*
 * Copyright 2021 Netsyms Technologies.
 * This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 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/.
 */

var keymgr;

/**
 * Load and unlock the private key in localstorage, prompting user as needed. If there is no key, generates, saves, and loads a new one.
 * @param {function} callback Passed two arguments: message for user, and boolean true if OK false if error.
 * @returns {undefined}
 */
function loadKeyFromLocalStorage(callback) {
    if (typeof keymgr != "undefined") {
        callback("Key already loaded.", true);
        return;
    }
    if (!inStorage("signingkey") || getStorage("signingkey") == "undefined") {
        var pass = prompt("Generating a new signing key (might take a while, be patient). Enter a password to protect it. You'll need to save this password somewhere safe; it cannot be recovered.");
        generatePrivateKey(getStorage("notary_name") + " <null@null.com>", pass, function (key) {
            if (typeof key == "undefined") {
                callback("Could not generate key.", false);
                return;
            }
            keymgr = key;
            setStorage("signingkey", keymgr.armored_pgp_private);
            callback("Signing key generated.", true);
        });
    } else {
        var pass = prompt("Enter password to unlock signing key:");
        loadPrivateKey(getStorage("signingkey"), pass, function (key) {
            if (typeof key == "undefined") {
                callback("Could not unlock key. Password is probably incorrect.", false);
                return;
            }
            keymgr = key;
            callback("Signing key unlocked.", true);
        });
    }
}

function loadKeyFromLocalStorageWithUserFeedback() {
    loadKeyFromLocalStorage(function (msg, ok) {
       if (ok) {
           alert(msg);
       } else {
           alert("Error: " + msg);
       }
    });
}

/**
 * Load a private key.
 * @param {string} armoredkey PGP private key
 * @param {string} pass key password
 * @param {function} callback Passed a new keymanager for the key.
 * @returns {undefined}
 */
function loadPrivateKey(armoredkey, pass, callback) {
    kbpgp.KeyManager.import_from_armored_pgp({
        armored: armoredkey
    }, function (err, key) {
        if (!err) {
            if (key.is_pgp_locked()) {
                key.unlock_pgp({
                    passphrase: pass
                }, function (err) {
                    if (!err) {
                        console.log("Loaded private key with passphrase");
                        callback(key);
                    } else {
                        console.error(err);
                        callback(undefined);
                    }
                });
            } else {
                console.log("Loaded private key w/o passphrase");
                callback(key);
            }
        } else {
            console.error(err);
            callback(undefined);
        }
    });
}

/**
 * Sign a message with a key and return the signed message in the callback.
 * @param {type} text
 * @param {type} key
 * @param {type} callback
 * @returns {undefined}
 */
function signMessage(text, key, callback) {
    var params = {
        msg: text,
        sign_with: key
    };
    kbpgp.box(params, function (err, result_string, result_buffer) {
        //console.log(err, result_string, result_buffer);
        callback(result_string);
    });
}

/**
 * Generate a new private key.
 * @param {string} userid Something like "Test User <test@netsyms.com>"
 * @param {string} passphrase protects the key
 * @param {function} callback Passed the keymanager for the new key
 * @returns {undefined}
 */
function generatePrivateKey(userid, passphrase, callback) {
    var F = kbpgp["const"].openpgp;

    var opts = {
        userid: userid,
        primary: {
            nbits: 2048,
            flags: F.certify_keys | F.sign_data | F.auth | F.encrypt_comm | F.encrypt_storage,
            expire_in: 0  // never expire
        },
        subkeys: []
    };

    kbpgp.KeyManager.generate(opts, function (err, alice) {
        if (!err) {
            alice.sign({}, function (err) {
                alice.export_pgp_private({
                    passphrase: passphrase
                }, function (err, pgp_private) {
                    callback(alice);
                });
            });
        }
    });
}

function exportPublicKey() {
    loadKeyFromLocalStorage(function (message, ok) {
        if (ok) {
            openSaveFileDialog(function (path) {
                keymgr.export_pgp_public({}, function (err, pgp_public) {
                    if (err) {
                        alert("Something went wrong.");
                    } else {
                        writeToFile(path, pgp_public);
                    }
                });
            }, "public-key.asc", ".asc");
        } else {
            alert("Error: " + message);
        }
    });
}

function exportPrivateKey() {
    loadKeyFromLocalStorage(function (message, ok) {
        if (ok) {
            var pass = prompt("Enter a password to protect the backup key:");
            openSaveFileDialog(function (path) {
                keymgr.export_pgp_private({
                    passphrase: pass
                }, function (err, pgp_private) {
                    if (err) {
                        alert("Something went wrong.");
                    } else {
                        writeToFile(path, pgp_private);
                    }
                });
            }, "private-key.asc", ".asc");
        } else {
            alert("Error: " + message);
        }
    });
}

function importPrivateKey() {
    if (inStorage("signingkey") && getStorage("signingkey") != "undefined") {
        if (!confirm("The restored key will replace the current key, which will be unrecoverable unless you made a backup. Continue?")) {
            return;
        }
    }
    openFileDialog(function (path) {
        var keyfile = getFileAsString(path);
        var pass = prompt("Enter password for imported key (password was set when exported):");
        loadPrivateKey(keyfile, pass, function (key) {
            if (typeof key == "undefined") {
                alert("Could not import key. Password is probably incorrect.");
                return;
            }
            keymgr = key;
            setStorage("signingkey", keymgr.armored_pgp_private);
            alert("Private key imported.");
        });
    }, ".asc");
}