/**
 * @module Numeric
 */
// copyright defined in eosjs/LICENSE.txt

// tslint:disable-next-line:no-var-requires
const ripemd160 = require("./ripemd").RIPEMD160.hash as (a: Uint8Array) => ArrayBuffer;

const base58Chars = "123456789ABCDEFGHJKLMNPQRSTUVWXYZabcdefghijkmnopqrstuvwxyz";
const base64Chars = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";

function create_base58_map() {
    const base58M = Array(256).fill(-1) as number[];
    for (let i = 0; i < base58Chars.length; ++i) {
        base58M[base58Chars.charCodeAt(i)] = i;
    }
    return base58M;
}

const base58Map = create_base58_map();

function create_base64_map() {
    const base64M = Array(256).fill(-1) as number[];
    for (let i = 0; i < base64Chars.length; ++i) {
        base64M[base64Chars.charCodeAt(i)] = i;
    }
    base64M["=".charCodeAt(0)] = 0;
    return base64M;
}

const base64Map = create_base64_map();

/** Is `bignum` a negative number? */
export function isNegative(bignum: Uint8Array) {
    return (bignum[bignum.length - 1] & 0x80) !== 0;
}

/** Negate `bignum` */
export function negate(bignum: Uint8Array) {
    let carry = 1;
    for (let i = 0; i < bignum.length; ++i) {
        const x = (~bignum[i] & 0xff) + carry;
        bignum[i] = x;
        carry = x >> 8;
    }
}

/**
 * Convert an unsigned decimal number in `s` to a bignum
 * @param size bignum size (bytes)
 */
export function decimalToBinary(size: number, s: string) {
    const result = new Uint8Array(size);
    for (let i = 0; i < s.length; ++i) {
        const srcDigit = s.charCodeAt(i);
        if (srcDigit < "0".charCodeAt(0) || srcDigit > "9".charCodeAt(0)) {
            throw new Error("invalid number");
        }
        let carry = srcDigit - "0".charCodeAt(0);
        for (let j = 0; j < size; ++j) {
            const x = result[j] * 10 + carry;
            result[j] = x;
            carry = x >> 8;
        }
        if (carry) {
            throw new Error("number is out of range");
        }
    }
    return result;
}

/**
 * Convert a signed decimal number in `s` to a bignum
 * @param size bignum size (bytes)
 */
export function signedDecimalToBinary(size: number, s: string) {
    const negative = s[0] === "-";
    if (negative) {
        s = s.substr(1);
    }
    const result = decimalToBinary(size, s);
    if (negative) {
        negate(result);
        if (!isNegative(result)) {
            throw new Error("number is out of range");
        }
    } else if (isNegative(result)) {
        throw new Error("number is out of range");
    }
    return result;
}

/**
 * Convert `bignum` to an unsigned decimal number
 * @param minDigits 0-pad result to this many digits
 */
export function binaryToDecimal(bignum: Uint8Array, minDigits = 1) {
    const result = Array(minDigits).fill("0".charCodeAt(0)) as number[];
    for (let i = bignum.length - 1; i >= 0; --i) {
        let carry = bignum[i];
        for (let j = 0; j < result.length; ++j) {
            const x = ((result[j] - "0".charCodeAt(0)) << 8) + carry;
            result[j] = "0".charCodeAt(0) + x % 10;
            carry = (x / 10) | 0;
        }
        while (carry) {
            result.push("0".charCodeAt(0) + carry % 10);
            carry = (carry / 10) | 0;
        }
    }
    result.reverse();
    return String.fromCharCode(...result);
}

/**
 * Convert `bignum` to a signed decimal number
 * @param minDigits 0-pad result to this many digits
 */
export function signedBinaryToDecimal(bignum: Uint8Array, minDigits = 1) {
    if (isNegative(bignum)) {
        const x = bignum.slice();
        negate(x);
        return "-" + binaryToDecimal(x, minDigits);
    }
    return binaryToDecimal(bignum, minDigits);
}

/**
 * Convert an unsigned base-58 number in `s` to a bignum
 * @param size bignum size (bytes)
 */
export function base58ToBinary(size: number, s: string) {
    const result = new Uint8Array(size);
    for (let i = 0; i < s.length; ++i) {
        let carry = base58Map[s.charCodeAt(i)];
        if (carry < 0) {
            throw new Error("invalid base-58 value");
        }
        for (let j = 0; j < size; ++j) {
            const x = result[j] * 58 + carry;
            result[j] = x;
            carry = x >> 8;
        }
        if (carry) {
            throw new Error("base-58 value is out of range");
        }
    }
    result.reverse();
    return result;
}

/**
 * Convert `bignum` to a base-58 number
 * @param minDigits 0-pad result to this many digits
 */
export function binaryToBase58(bignum: Uint8Array, minDigits = 1) {
    const result = [] as number[];
    for (const byte of bignum) {
        let carry = byte;
        for (let j = 0; j < result.length; ++j) {
            const x = (base58Map[result[j]] << 8) + carry;
            result[j] = base58Chars.charCodeAt(x % 58);
            carry = (x / 58) | 0;
        }
        while (carry) {
            result.push(base58Chars.charCodeAt(carry % 58));
            carry = (carry / 58) | 0;
        }
    }
    for (const byte of bignum) {
        if (byte) {
            break;
        } else {
            result.push("1".charCodeAt(0));
        }
    }
    result.reverse();
    return String.fromCharCode(...result);
}

/** Convert an unsigned base-64 number in `s` to a bignum */
export function base64ToBinary(s: string) {
    let len = s.length;
    if ((len & 3) === 1 && s[len - 1] === "=") {
        len -= 1;
    } // fc appends an extra '='
    if ((len & 3) !== 0) {
        throw new Error("base-64 value is not padded correctly");
    }
    const groups = len >> 2;
    let bytes = groups * 3;
    if (len > 0 && s[len - 1] === "=") {
        if (s[len - 2] === "=") {
            bytes -= 2;
        } else {
            bytes -= 1;
        }
    }
    const result = new Uint8Array(bytes);

    for (let group = 0; group < groups; ++group) {
        const digit0 = base64Map[s.charCodeAt(group * 4 + 0)];
        const digit1 = base64Map[s.charCodeAt(group * 4 + 1)];
        const digit2 = base64Map[s.charCodeAt(group * 4 + 2)];
        const digit3 = base64Map[s.charCodeAt(group * 4 + 3)];
        result[group * 3 + 0] = (digit0 << 2) | (digit1 >> 4);
        if (group * 3 + 1 < bytes) {
            result[group * 3 + 1] = ((digit1 & 15) << 4) | (digit2 >> 2);
        }
        if (group * 3 + 2 < bytes) {
            result[group * 3 + 2] = ((digit2 & 3) << 6) | digit3;
        }
    }
    return result;
}

/** Key types this library supports */
export const enum KeyType {
    k1 = 0,
    r1 = 1,
}

/** Public key data size, excluding type field */
export const publicKeyDataSize = 33;

/** Private key data size, excluding type field */
export const privateKeyDataSize = 32;

/** Signature data size, excluding type field */
export const signatureDataSize = 65;

/** Public key, private key, or signature in binary form */
export interface Key {
    type: KeyType;
    data: Uint8Array;
}

function digestSuffixRipemd160(data: Uint8Array, suffix: string) {
    const d = new Uint8Array(data.length + suffix.length);
    for (let i = 0; i < data.length; ++i) {
        d[i] = data[i];
    }
    for (let i = 0; i < suffix.length; ++i) {
        d[data.length + i] = suffix.charCodeAt(i);
    }
    return ripemd160(d);
}

function stringToKey(s: string, type: KeyType, size: number, suffix: string): Key {
    const whole = base58ToBinary(size + 4, s);
    const result = { type, data: new Uint8Array(whole.buffer, 0, size) };
    const digest = new Uint8Array(digestSuffixRipemd160(result.data, suffix));
    if (digest[0] !== whole[size + 0] || digest[1] !== whole[size + 1]
        || digest[2] !== whole[size + 2] || digest[3] !== whole[size + 3]) {
        throw new Error("checksum doesn't match");
    }
    return result;
}

function keyToString(key: Key, suffix: string, prefix: string) {
    const digest = new Uint8Array(digestSuffixRipemd160(key.data, suffix));
    const whole = new Uint8Array(key.data.length + 4);
    for (let i = 0; i < key.data.length; ++i) {
        whole[i] = key.data[i];
    }
    for (let i = 0; i < 4; ++i) {
        whole[i + key.data.length] = digest[i];
    }
    return prefix + binaryToBase58(whole);
}

/** Convert key in `s` to binary form */
export function stringToPublicKey(s: string): Key {
    if (typeof s !== "string") {
        throw new Error("expected string containing public key");
    }
    if (s.substr(0, 3) === "GLS") {
        const whole = base58ToBinary(publicKeyDataSize + 4, s.substr(3));
        const key = { type: KeyType.k1, data: new Uint8Array(publicKeyDataSize) };
        for (let i = 0; i < publicKeyDataSize; ++i) {
            key.data[i] = whole[i];
        }
        const digest = new Uint8Array(ripemd160(key.data));
        if (digest[0] !== whole[publicKeyDataSize] || digest[1] !== whole[34]
            || digest[2] !== whole[35] || digest[3] !== whole[36]) {
            throw new Error("checksum doesn't match");
        }
        return key;
    } else if (s.substr(0, 7) === "PUB_K1_") {
        return stringToKey(s.substr(7), KeyType.k1, publicKeyDataSize, "K1");
    } else if (s.substr(0, 7) === "PUB_R1_") {
        return stringToKey(s.substr(7), KeyType.r1, publicKeyDataSize, "R1");
    } else {
        throw new Error("unrecognized public key format");
    }
}

/** Convert `key` to string (base-58) form */
export function publicKeyToString(key: Key) {
    if (key.type === KeyType.k1 && key.data.length === publicKeyDataSize) {
        return keyToString(key, "K1", "PUB_K1_");
    } else if (key.type === KeyType.r1 && key.data.length === publicKeyDataSize) {
        return keyToString(key, "R1", "PUB_R1_");
    } else {
        throw new Error("unrecognized public key format");
    }
}

/** If a key is in the legacy format (`EOS` prefix), then convert it to the new format (`PUB_K1_`).
 * Leaves other formats untouched
 */
export function convertLegacyPublicKey(s: string) {
    if (s.substr(0, 3) === "GLS") {
        return publicKeyToString(stringToPublicKey(s));
    }
    return s;
}

/** If a key is in the legacy format (`EOS` prefix), then convert it to the new format (`PUB_K1_`).
 * Leaves other formats untouched
 */
export function convertLegacyPublicKeys(keys: string[]) {
    return keys.map(convertLegacyPublicKey);
}

/** Convert key in `s` to binary form */
export function stringToPrivateKey(s: string): Key {
    if (typeof s !== "string") {
        throw new Error("expected string containing private key");
    }
    if (s.substr(0, 7) === "PVT_R1_") {
        return stringToKey(s.substr(7), KeyType.r1, privateKeyDataSize, "R1");
    } else {
        throw new Error("unrecognized private key format");
    }
}

/** Convert `key` to string (base-58) form */
export function privateKeyToString(key: Key) {
    if (key.type === KeyType.r1) {
        return keyToString(key, "R1", "PVT_R1_");
    } else {
        throw new Error("unrecognized private key format");
    }
}

/** Convert key in `s` to binary form */
export function stringToSignature(s: string): Key {
    if (typeof s !== "string") {
        throw new Error("expected string containing signature");
    }
    if (s.substr(0, 7) === "SIG_K1_") {
        return stringToKey(s.substr(7), KeyType.k1, signatureDataSize, "K1");
    } else if (s.substr(0, 7) === "SIG_R1_") {
        return stringToKey(s.substr(7), KeyType.r1, signatureDataSize, "R1");
    } else {
        throw new Error("unrecognized signature format");
    }
}

/** Convert `signature` to string (base-58) form */
export function signatureToString(signature: Key) {
    if (signature.type === KeyType.k1) {
        return keyToString(signature, "K1", "SIG_K1_");
    } else if (signature.type === KeyType.r1) {
        return keyToString(signature, "R1", "SIG_R1_");
    } else {
        throw new Error("unrecognized signature format");
    }
}