-- Prosody IM

-- Copyright (C) 2008-2010 Matthew Wild

-- Copyright (C) 2008-2010 Waqas Hussain

--

-- This project is MIT/X11 licensed. Please see the

-- COPYING file in the source package for more information.

--

local t_insert, t_sort, t_remove, t_concat

    = table.insert, table.sort, table.remove, table.concat;

local setmetatable = setmetatable;

local math_random = math.random;

local math_floor = math.floor;

local pairs, ipairs = pairs, ipairs;

local tostring = tostring;

local type = type;

local array = {};

local array_base = {};

local array_methods = {};

local array_mt = {

	__index = array_methods;

	__name = "array";

	__tostring = function (self) return "{"..self:concat(", ").."}"; end;

};

function array_mt:__freeze() return self; end

local function new_array(self, t, _s, _var)

	if type(t) == "function" then -- Assume iterator

		t = self.collect(t, _s, _var);

	end

	return setmetatable(t or {}, array_mt);

end

function array_mt.__add(a1, a2)

	local res = new_array();

	return res:append(a1):append(a2);

end

function array_mt.__eq(a, b)

	if #a == #b then

		for i = 1, #a do

			if a[i] ~= b[i] then

				return false;

			end

		end

	else

		return false;

	end

	return true;

end

function array_mt.__div(a1, func)

	local a2 = new_array();

	local o = 0;

	for i = 1, #a1 do

		local new_value = func(a1[i]);

		if new_value ~= nil then

			o = o + 1;

			a2[o] = new_value;

		end

	end

	return a2;

end

setmetatable(array, { __call = new_array });

-- Read-only methods

function array_methods:random()

	return self[math_random(1, #self)];

end

-- Return a random value excluding the one at idx

function array_methods:random_other(idx)

	local max = #self;

	return self[((math.random(1, max-1)+(idx-1))%max)+1];

end

-- These methods can be called two ways:

--   array.method(existing_array, [params [, ...]]) -- Create new array for result

--   existing_array:method([params, ...]) -- Transform existing array into result

--

function array_base.map(outa, ina, func)

	for k, v in ipairs(ina) do

		outa[k] = func(v);

	end

	return outa;

end

function array_base.filter(outa, ina, func)

	local inplace, start_length = ina == outa, #ina;

	local write = 1;

	for read = 1, start_length do

		local v = ina[read];

		if func(v) then

			outa[write] = v;

			write = write + 1;

		end

	end

	if inplace and write <= start_length then

		for i = write, start_length do

			outa[i] = nil;

		end

	end

	return outa;

end

function array_base.sort(outa, ina, ...)

	if ina ~= outa then

		outa:append(ina);

	end

	t_sort(outa, ...);

	return outa;

end

function array_base.unique(outa, ina)

	local seen = {};

	return array_base.filter(outa, ina, function (item)

		if seen[item] then

			return false;

		else

			seen[item] = true;

			return true;

		end

	end);

end

function array_base.pluck(outa, ina, key)

	for i = 1, #ina do

		outa[i] = ina[i][key];

	end

	return outa;

end

function array_base.reverse(outa, ina)

	local len = #ina;

	if ina == outa then

		local middle = math_floor(len/2);

		len = len + 1;

		local o; -- opposite

		for i = 1, middle do

			o = len - i;

			outa[i], outa[o] = outa[o], outa[i];

		end

	else

		local off = len + 1;

		for i = 1, len do

			outa[i] = ina[off - i];

		end

	end

	return outa;

end

--- These methods only mutate the array

function array_methods:shuffle()

	local len = #self;

	for i = 1, #self do

		local r = math_random(i, len);

		self[i], self[r] = self[r], self[i];

	end

	return self;

end

function array_methods:append(ina)

	local len, len2 = #self, #ina;

	for i = 1, len2 do

		self[len+i] = ina[i];

	end

	return self;

end

function array_methods:push(x)

	t_insert(self, x);

	return self;

end

array_methods.pop = t_remove;

function array_methods:concat(sep)

	return t_concat(array.map(self, tostring), sep);

end

function array_methods:length()

	return #self;

end

--- These methods always create a new array

function array.collect(f, s, var)

	local t = {};

	while true do

		var = f(s, var);

		if var == nil then break; end

		t_insert(t, var);

	end

	return setmetatable(t, array_mt);

end

---

-- Setup methods from array_base

for method, f in pairs(array_base) do

	local base_method = f;

	-- Setup global array method which makes new array

	array[method] = function (old_a, ...)

		local a = new_array();

		return base_method(a, old_a, ...);

	end

	-- Setup per-array (mutating) method

	array_methods[method] = function (self, ...)

		return base_method(self, self, ...);

	end

end

return array;