local dbuffer = require "util.dbuffer";

describe("util.dbuffer", function ()

	describe("#new", function ()

		it("has a constructor", function ()

			assert.Function(dbuffer.new);

		end);

		it("can be created", function ()

			assert.truthy(dbuffer.new());

		end);

		it("won't create an empty buffer", function ()

			assert.falsy(dbuffer.new(0));

		end);

		it("won't create a negatively sized buffer", function ()

			assert.falsy(dbuffer.new(-1));

		end);

	end);

	describe(":write", function ()

		local b = dbuffer.new();

		it("works", function ()

			assert.truthy(b:write("hi"));

		end);

	end);

	describe(":read", function ()

		it("supports optional bytes parameter", function ()

			-- should return the frontmost chunk

			local b = dbuffer.new();

			assert.truthy(b:write("hello"));

			assert.truthy(b:write(" "));

			assert.truthy(b:write("world"));

			assert.equal("h", b:read(1));

			assert.equal("ello", b:read());

			assert.equal(" ", b:read());

			assert.equal("world", b:read());

		end);

	end);

	describe(":discard", function ()

		local b = dbuffer.new();

		it("works", function ()

			assert.truthy(b:write("hello world"));

			assert.truthy(b:discard(6));

			assert.equal(5, b:length());

			assert.equal("world", b:read(5));

		end);

	end);

	describe(":collapse()", function ()

		it("works on an empty buffer", function ()

			local b = dbuffer.new();

			b:collapse();

		end);

	end);

	describe(":sub", function ()

		-- Helper function to compare buffer:sub() with string:sub()

		local s = "hello world";

		local function test_sub(b, x, y)

			local string_result, buffer_result = s:sub(x, y), b:sub(x, y);

			assert.equals(string_result, buffer_result, ("buffer:sub(%d, %s) does not match string:sub()"):format(x, y and ("%d"):format(y) or "nil"));

		end

		it("works", function ()

			local b = dbuffer.new();

			assert.truthy(b:write("hello world"));

			assert.equals("hello", b:sub(1, 5));

		end);

		it("works after discard", function ()

			local b = dbuffer.new(256);

			assert.equals("foobar", b:sub(1, 6));

			assert.equals("bar", b:sub(1, 3));

		end);

		it("supports optional end parameter", function ()

			local b = dbuffer.new();

			assert.truthy(b:write("hello world"));

			assert.equals("hello world", b:sub(1));

			assert.equals("world", b:sub(-5));

		end);

		it("is equivalent to string:sub", function ()

			local b = dbuffer.new(11);

			assert.truthy(b:write(s));

			for i = -13, 13 do

				for j = -13, 13 do

					test_sub(b, i, j);

				end

			end

		end);

	end);

	describe(":byte", function ()

		-- Helper function to compare buffer:byte() with string:byte()

		local s = "hello world"

		local function test_byte(b, x, y)

			local string_result, buffer_result = {s:byte(x, y)}, {b:byte(x, y)};

			assert.same(string_result, buffer_result, ("buffer:byte(%d, %s) does not match string:byte()"):format(x, y and ("%d"):format(y) or "nil"));

		end

		it("is equivalent to string:byte", function ()

			local b = dbuffer.new(11);

			assert.truthy(b:write(s));

			test_byte(b, 1);

			test_byte(b, 3);

			test_byte(b, -1);

			test_byte(b, -3);

			for i = -13, 13 do

				for j = -13, 13 do

					test_byte(b, i, j);

				end

			end

		end);

		it("works with characters > 127", function ()

			local b = dbuffer.new();

			b:write(string.char(0, 140));

			local r = { b:byte(1, 2) };

			assert.same({ 0, 140 }, r);

		end);

		it("works on an empty buffer", function ()

			local b = dbuffer.new();

			assert.equal("", b:sub(1,1));

		end);

	end);

end);