/*!
 * config.js - configuration parsing for bcoin
 * Copyright (c) 2016-2017, Christopher Jeffrey (MIT License).
 * https://github.com/bcoin-org/bcoin
 */

"use strict";

import assert from "bsert";
import Path from "path";
import os from "os";
import fs from "fs";

const HOME = os.homedir ? os.homedir() : "/";

export interface Options {
  suffix?: string;
  fallback?: string;
  alias?: object;
}

export interface LoadOptions {
  hash?: string;
  query?: string;
  env?: object;
  argv?: string[];
  config?: string;
}

/**
 * Config Parser
 */

class Config {
  private module: string;
  private prefix: string;
  private suffix?: string;
  private fallback?: string;
  private options: Options;
  private alias = {};
  private data = {};
  private env = {};
  private args = {};
  private argv: any[] = [];
  private pass: any[] = [];
  private query = {};
  private hash = {};

  constructor(module: string, options?: Options) {
    assert(typeof module === "string");
    assert(module.length > 0);

    this.module = module;
    this.prefix = Path.join(HOME, `.${module}`);

    if (options) {
      this.init(options);
    }
  }

  private init(options: Options) {
    assert(options && typeof options === "object");

    if (options.suffix != null) {
      assert(typeof options.suffix === "string");
      this.suffix = options.suffix;
    }

    if (options.fallback != null) {
      assert(typeof options.fallback === "string");
      this.fallback = options.fallback;
    }

    if (options.alias) {
      assert(typeof options.alias === "object");
      for (const key of Object.keys(options.alias)) {
        const value = options.alias[key];
        assert(typeof value === "string");
        this.alias[key] = value;
      }
    }
  }
  public inject(options: object) {
    for (const key of Object.keys(options)) {
      const value = options[key];

      switch (key) {
        case "hash":
        case "query":
        case "env":
        case "argv":
        case "config":
          continue;
      }

      this.set(key, value);
    }
  }

  public load(options: LoadOptions) {
    if (options.hash) {
      this.parseHash(options.hash);
    }

    if (options.query) {
      this.parseQuery(options.query);
    }

    if (options.env) {
      this.parseEnv(options.env);
    }

    if (options.argv) {
      this.parseArg(options.argv);
    }

    this.prefix = this.getPrefix();
  }

  public open(file: string) {
    const path = this.getFile(file);

    let text;
    try {
      text = fs.readFileSync(path, "utf8");
    } catch (e) {
      if (e.code === "ENOENT") return;
      throw e;
    }

    this.parseConfig(text);

    this.prefix = this.getPrefix();
  }

  public openDir(dir: string) {
    assert(fs.existsSync(dir), `Directory ${dir} does not exist`);

    let files = fs.readdirSync(dir).map((item) => Path.join(dir, item));
    files.forEach(this.openJson);
  }

  public openJson(file: string) {
    const path = this.getFile(file);

    let json;
    try {
      json = fs.readFileSync(path, "utf8");
      json = JSON.parse(json);
    } catch (e) {
      if (e.code === "ENOENT") return;
      throw e;
    }

    assert(typeof json === "object", `Config file ${file} must be an object`);

    for (const key of Object.keys(json)) {
      const value = json[key];

      switch (value) {
        case Array.isArray(value):
          let newVal = this.array(key) ?? [];
          newVal.push(value);
          this.set(key, newVal);
          break;
        default:
          this.set(key, value);
          break;
      }
    }

    this.prefix = this.getPrefix();
  }

  public filter(name: string) {
    assert(typeof name === "string");

    const child = new Config(this.module);

    child.prefix = this.prefix;
    child.suffix = this.suffix;
    child.fallback = this.fallback;
    child.argv = this.argv;
    child.pass = this.pass;

    _filter(name, this.env, child.env);
    _filter(name, this.args, child.args);
    _filter(name, this.query, child.query);
    _filter(name, this.hash, child.hash);
    _filter(name, this.options, child.options);

    return child;
  }

  public set(key: string, value: any) {
    assert(typeof key === "string", "Key must be a string.");

    if (value == null) {
      return;
    }

    key = key.replace(/-/g, "");
    key = key.toLowerCase();

    this.options[key] = value;
  }

  public has(key: string) {
    if (typeof key === "number") {
      assert(key >= 0, "Index must be positive.");
      return key < this.argv.length;
    }

    assert(typeof key === "string", "Key must be a string.");

    key = key.replace(/-/g, "");
    key = key.toLowerCase();

    if (this.hash[key] !== null) {
      return true;
    }

    if (this.query[key] !== null) {
      return true;
    }

    if (this.args[key] !== null) {
      return true;
    }

    if (this.env[key] !== null) {
      return true;
    }

    if (this.data[key] !== null) {
      return true;
    }

    return this.options[key] !== null;
  }

  public get(key: string, fallback = null) {
    if (Array.isArray(key)) {
      const keys = key;
      for (const key of keys) {
        const value = this.get(key);
        if (value !== null) {
          return value;
        }
      }
      return fallback;
    }

    if (typeof key === "number") {
      assert(key >= 0, "Index must be positive.");

      if (key >= this.argv.length) {
        return fallback;
      }

      if (this.argv[key] != null) {
        return this.argv[key];
      }

      return fallback;
    }

    assert(typeof key === "string", "Key must be a string.");

    key = key.replace(/-/g, "");
    key = key.toLowerCase();

    if (this.hash[key] !== null) {
      return this.hash[key];
    }

    if (this.query[key] !== null) {
      return this.query[key];
    }

    if (this.args[key] !== null) {
      return this.args[key];
    }

    if (this.env[key] !== null) {
      return this.env[key];
    }

    if (this.data[key] !== null) {
      return this.data[key];
    }

    if (this.options[key] !== null) {
      return this.options[key];
    }

    return fallback;
  }

  public typeOf(key: string) {
    const value = this.get(key);

    if (value === null) {
      return "null";
    }

    return typeof value;
  }

  public str(key: string, fallback = null) {
    const value = this.get(key);

    if (value === null) {
      return fallback;
    }

    if (typeof value !== "string") {
      throw new Error(`${fmt(key)} must be a string.`);
    }

    return value;
  }
  int(key, fallback = null) {
    const value = this.get(key);

    if (value === null) {
      return fallback;
    }

    if (typeof value !== "string") {
      if (typeof value !== "number") {
        throw new Error(`${fmt(key)} must be an int.`);
      }

      if (!Number.isSafeInteger(value)) {
        throw new Error(`${fmt(key)} must be an int.`);
      }

      return value;
    }

    if (!/^\-?\d+$/.test(value)) {
      throw new Error(`${fmt(key)} must be an int.`);
    }

    const num = parseInt(value, 10);

    if (!Number.isSafeInteger(num)) {
      throw new Error(`${fmt(key)} must be an int.`);
    }

    return num;
  }

  uint(key, fallback = null) {
    const value = this.int(key);

    if (value === null) {
      return fallback;
    }

    if (value < 0) {
      throw new Error(`${fmt(key)} must be a uint.`);
    }

    return value;
  }

  float(key, fallback = null) {
    const value = this.get(key);

    if (value === null) {
      return fallback;
    }

    if (typeof value !== "string") {
      if (typeof value !== "number") {
        throw new Error(`${fmt(key)} must be a float.`);
      }

      if (!isFinite(value)) {
        throw new Error(`${fmt(key)} must be a float.`);
      }

      return value;
    }

    if (!/^\-?\d*(?:\.\d*)?$/.test(value)) {
      throw new Error(`${fmt(key)} must be a float.`);
    }

    if (!/\d/.test(value)) {
      throw new Error(`${fmt(key)} must be a float.`);
    }

    const num = parseFloat(value);

    if (!isFinite(num)) {
      throw new Error(`${fmt(key)} must be a float.`);
    }

    return num;
  }
  ufloat(key, fallback = null) {
    const value = this.float(key);
    if (value === null) {
      return fallback;
    }

    if (value < 0) {
      throw new Error(`${fmt(key)} must be a positive float.`);
    }

    return value;
  }

  fixed(key, exp, fallback = null) {
    const value = this.float(key);

    if (value === null) {
      return fallback;
    }

    try {
      return fromFloat(value, exp || 0);
    } catch (e) {
      throw new Error(`${fmt(key)} must be a fixed number.`);
    }
  }
  ufixed(key, exp, fallback = null) {
    const value = this.fixed(key, exp);

    if (value === null) {
      return fallback;
    }

    if (value < 0) {
      throw new Error(`${fmt(key)} must be a positive fixed number.`);
    }

    return value;
  }

  bool(key, fallback = null) {
    const value = this.get(key);

    if (value === null) {
      return fallback;
    }

    // Bitcoin Core compat.
    if (typeof value === "number") {
      if (value === 1) {
        return true;
      }

      if (value === 0) {
        return false;
      }
    }

    if (typeof value !== "string") {
      if (typeof value !== "boolean") {
        throw new Error(`${fmt(key)} must be a boolean.`);
      }
      return value;
    }

    if (value === "true" || value === "1") {
      return true;
    }

    if (value === "false" || value === "0") {
      return false;
    }

    throw new Error(`${fmt(key)} must be a boolean.`);
  }
  buf(key: string, fallback = null, enc: BufferEncoding = "hex") {
    const value = this.get(key);

    if (value === null) {
      return fallback;
    }

    if (typeof value !== "string") {
      if (!Buffer.isBuffer(value)) {
        throw new Error(`${fmt(key)} must be a buffer.`);
      }
      return value;
    }

    const data = Buffer.from(value, enc);

    if (data.length !== Buffer.byteLength(value, enc)) {
      throw new Error(`${fmt(key)} must be a ${enc} string.`);
    }

    return data;
  }

  public array(key: string, fallback = null) {
    const value = this.get(key);

    if (value === null) {
      return fallback;
    }

    if (typeof value !== "string") {
      if (!Array.isArray(value)) {
        throw new Error(`${fmt(key)} must be an array.`);
      }
      return value;
    }

    const parts = value.trim().split(/\s*,\s*/);
    const result = [];
    for (const part of parts) {
      if (part.length === 0) {
        continue;
      }

      result.push(part);
    }

    return result;
  }

  public obj(key: string, fallback = null) {
    const value = this.get(key);

    if (value === null) {
      return fallback;
    }

    if (typeof value !== "object" || Array.isArray(value)) {
      throw new Error(`${fmt(key)} must be an object.`);
    }

    return value;
  }

  public func(key: string, fallback = null) {
    const value = this.get(key);

    if (value === null) {
      return fallback;
    }

    if (typeof value !== "function") {
      throw new Error(`${fmt(key)} must be a function.`);
    }

    return value;
  }

  public path(key: string, fallback = null) {
    let value = this.str(key);
    if (value === null) {
      return fallback;
    }

    if (value.length === 0) {
      return fallback;
    }

    switch (value[0]) {
      case "~": // home dir
        value = Path.join(HOME, value.substring(1));
        break;
      case "@": // prefix
        value = Path.join(this.prefix, value.substring(1));
        break;
      default: // cwd
        break;
    }

    return Path.normalize(value);
  }

  public mb(key: string, fallback = null) {
    const value = this.uint(key);

    if (value === null) {
      return fallback;
    }

    return value * 1024 * 1024;
  }

  public getSuffix() {
    if (!this.suffix) {
      throw new Error("No suffix presented.");
    }

    const suffix = this.str(this.suffix, this.fallback);

    assert(isAlpha(suffix), "Bad suffix.");

    return suffix;
  }

  public getPrefix() {
    let prefix = this.str("prefix");

    if (prefix) {
      if (prefix[0] === "~") {
        prefix = Path.join(HOME, prefix.substring(1));
      }
    } else {
      prefix = Path.join(HOME, `.${this.module}`);
    }

    if (this.suffix) {
      const suffix = this.str(this.suffix);

      if (suffix) {
        assert(isAlpha(suffix), "Bad suffix.");
        if (this.fallback && suffix !== this.fallback) {
          prefix = Path.join(prefix, suffix);
        }
      }
    }

    return Path.normalize(prefix);
  }

  public getFile(file: string) {
    const name = this.str("config");

    if (name) {
      return name;
    }

    return Path.join(this.prefix, file);
  }

  public location(file: string) {
    return Path.join(this.prefix, file);
  }

  public parseConfig(text: string) {
    assert(typeof text === "string", "Config must be text.");

    if (text.charCodeAt(0) === 0xfeff) {
      text = text.substring(1);
    }

    text = text.replace(/\r\n/g, "\n");
    text = text.replace(/\r/g, "\n");
    text = text.replace(/\\\n/g, "");

    let num = 0;

    for (const chunk of text.split("\n")) {
      const line = chunk.trim();

      num += 1;

      if (line.length === 0) {
        continue;
      }

      if (line[0] === "#") {
        continue;
      }

      const index = line.indexOf(":");

      if (index === -1) {
        throw new Error(`Expected ':' on line ${num}: "${line}".`);
      }

      let key = line.substring(0, index).trim();

      key = key.replace(/\-/g, "");

      if (!isLowerKey(key)) {
        throw new Error(`Invalid option on line ${num}: ${key}.`);
      }

      const value = line.substring(index + 1).trim();

      if (value.length === 0) {
        continue;
      }

      const alias = this.alias[key];

      if (alias) {
        key = alias;
      }

      this.data[key] = value;
    }
  }

  public parseArg(argv?: string[]) {
    if (!argv || typeof argv !== "object") argv = process.argv;

    assert(Array.isArray(argv));

    let last = null;
    let pass = false;

    for (let i = 2; i < argv.length; i++) {
      const arg = argv[i];

      assert(typeof arg === "string");

      if (arg === "--") {
        pass = true;
        continue;
      }

      if (pass) {
        this.pass.push(arg);
        continue;
      }

      if (arg.length === 0) {
        last = null;
        continue;
      }

      if (arg.indexOf("--") === 0) {
        const index = arg.indexOf("=");

        let key = null;
        let value = null;
        let empty = false;

        if (index !== -1) {
          // e.g. --opt=val
          key = arg.substring(2, index);
          value = arg.substring(index + 1);
          last = null;
          empty = false;
        } else {
          // e.g. --opt
          key = arg.substring(2);
          value = "true";
          last = null;
          empty = true;
        }

        key = key.replace(/\-/g, "");

        if (!isLowerKey(key)) {
          throw new Error(`Invalid argument: --${key}.`);
        }

        if (value.length === 0) {
          continue;
        }

        // Do not allow one-letter aliases.
        if (key.length > 1) {
          const alias = this.alias[key];
          if (alias) {
            key = alias;
          }
        }

        this.args[key] = value;

        if (empty) {
          last = key;
        }

        continue;
      }

      if (arg[0] === "-") {
        // e.g. -abc
        last = null;

        for (let j = 1; j < arg.length; j++) {
          let key = arg[j];

          if (
            (key < "a" || key > "z") &&
            (key < "A" || key > "Z") &&
            (key < "0" || key > "9") &&
            key !== "?"
          ) {
            throw new Error(`Invalid argument: -${key}.`);
          }

          const alias = this.alias[key];

          if (alias) {
            key = alias;
          }

          this.args[key] = "true";

          last = key;
        }

        continue;
      }

      // e.g. foo
      const value = arg;

      if (value.length === 0) {
        last = null;
        continue;
      }

      if (last) {
        this.args[last] = value;
        last = null;
      } else {
        this.argv.push(value);
      }
    }
  }

  public parseEnv(env?: object) {
    let prefix = this.module;

    prefix = prefix.toUpperCase();
    prefix = prefix.replace(/-/g, "_");
    prefix += "_";

    if (!env || typeof env !== "object") {
      env = process.env;
    }

    assert(env && typeof env === "object");

    for (let key of Object.keys(env)) {
      const value = env[key];

      assert(typeof value === "string");

      if (key.indexOf(prefix) !== 0) continue;

      key = key.substring(prefix.length);
      key = key.replace(/_/g, "");

      if (!isUpperKey(key)) {
        continue;
      }

      if (value.length === 0) {
        continue;
      }

      key = key.toLowerCase();

      // Do not allow one-letter aliases.
      if (key.length > 1) {
        const alias = this.alias[key];
        if (alias) {
          key = alias;
        }
      }

      this.env[key] = value;
    }
  }

  public parseQuery(query: string) {
    if (typeof query !== "string") {
      if (!global.location) {
        return {};
      }

      query = global.location.search;

      if (typeof query !== "string") {
        return {};
      }
    }

    return this.parseForm(query, "?", this.query);
  }
  public parseHash(hash: string) {
    if (typeof hash !== "string") {
      if (!global.location) {
        return {};
      }

      hash = global.location.hash;

      if (typeof hash !== "string") {
        return {};
      }
    }

    return this.parseForm(hash, "#", this.hash);
  }

  public parseForm(query: string, ch: string, map: object) {
    assert(typeof query === "string");

    if (query.length === 0) {
      return;
    }

    if (query[0] === ch) {
      query = query.substring(1);
    }

    for (const pair of query.split("&")) {
      const index = pair.indexOf("=");

      let key, value;
      if (index !== -1) {
        key = pair.substring(0, index);
        value = pair.substring(index + 1);
      } else {
        key = pair;
        value = "true";
      }

      key = unescape(key);
      key = key.replace(/\-/g, "");

      if (!isLowerKey(key)) {
        continue;
      }

      value = unescape(value);

      if (value.length === 0) {
        continue;
      }

      const alias = this.alias[key];

      if (alias) {
        key = alias;
      }

      map[key] = value;
    }
  }
}

/*
 * Helpers
 */

function fmt(key: string[] | string | number) {
  if (Array.isArray(key)) {
    key = key[0];
  }

  if (typeof key === "number") {
    return `Argument #${key}`;
  }

  return key;
}

function unescape(str: string) {
  try {
    str = decodeURIComponent(str);
    str = str.replace(/\+/g, " ");
  } catch (e) {}
  str = str.replace(/\0/g, "");
  return str;
}

function isAlpha(str: string) {
  return /^[a-z0-9_\-]+$/i.test(str);
}

function isKey(key: string) {
  return /^[a-zA-Z0-9]+$/.test(key);
}

function isLowerKey(key: string) {
  if (!isKey(key)) {
    return false;
  }

  return !/[A-Z]/.test(key);
}

function isUpperKey(key: string) {
  if (!isKey(key)) {
    return false;
  }

  return !/[a-z]/.test(key);
}

function _filter(name: string, a: object | any[], b: object | any[]) {
  for (const key of Object.keys(a)) {
    if (key.length > name.length && key.indexOf(name) === 0) {
      const sub = key.substring(name.length);
      b[sub] = a[key];
    }
  }
}

function fromFloat(num: number, exp: number) {
  assert(typeof num === "number" && isFinite(num));
  assert(Number.isSafeInteger(exp));

  let str = num.toFixed(exp);
  let sign = 1;

  if (str.length > 0 && str[0] === "-") {
    str = str.substring(1);
    sign = -1;
  }

  let hi: number | string = str;
  let lo: number | string = "0";

  const index = str.indexOf(".");

  if (index !== -1) {
    hi = str.substring(0, index);
    lo = str.substring(index + 1);
  }

  hi = hi.replace(/^0+/, "");
  lo = lo.replace(/0+$/, "");

  assert(hi.length <= 16 - exp, "Fixed number string exceeds 2^53-1.");

  assert(lo.length <= exp, "Too many decimal places in fixed number string.");

  if (hi.length === 0) {
    hi = "0";
  }

  while (lo.length < exp) {
    lo += "0";
  }

  if (lo.length === 0) {
    lo = "0";
  }

  assert(
    /^\d+$/.test(hi) && /^\d+$/.test(lo),
    "Non-numeric characters in fixed number string."
  );

  hi = parseInt(hi, 10);
  lo = parseInt(lo, 10);

  const mult = Math.pow(10, exp);
  const maxLo = Number.MAX_SAFE_INTEGER % mult;
  const maxHi = (Number.MAX_SAFE_INTEGER - maxLo) / mult;

  assert(
    hi < maxHi || (hi === maxHi && lo <= maxLo),
    "Fixed number string exceeds 2^53-1."
  );

  return sign * (hi * mult + lo);
}