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());

			assert.truthy(dbuffer.new(1));

			assert.truthy(dbuffer.new(1024));

		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(10, 3);

		it("works", function ()

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

		end);

		it("fails when the buffer is full", function ()

			local ret = b:write(" there world, this is a long piece of data");

			assert.is_falsy(ret);

		end);

		it("works when max_chunks is reached", function ()

			-- Chunks are an optimization, dbuffer should collapse chunks when needed

			for _ = 1, 8 do

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

			end

			assert.falsy(b:write("!")); -- Length reached

		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);

		it("fails when there is not enough data in the buffer", function ()

			local b = dbuffer.new(12);

			b:write("hello");

			b:write(" ");

			b:write("world");

			assert.is_falsy(b:read(12));

			assert.is_falsy(b:read(13));

		end);

	end);

	describe(":read_until", function ()

		it("works", function ()

			local b = dbuffer.new();

			b:write("hello\n");

			b:write("world");

			b:write("\n");

			b:write("\n\n");

			b:write("stuff");

			b:write("more\nand more");

			assert.equal(nil, b:read_until("."));

			assert.equal(nil, b:read_until("%"));

			assert.equal("hello\n", b:read_until("\n"));

			assert.equal("world\n", b:read_until("\n"));

			assert.equal("\n", b:read_until("\n"));

			assert.equal("\n", b:read_until("\n"));

			assert.equal("stu", b:read(3));

			assert.equal("ffmore\n", b:read_until("\n"));

			assert.equal(nil, b:read_until("\n"));

			assert.equal("and more", b:read_chunk());

		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(5, b:len());

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

		end);

		it("works across chunks", function ()

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

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

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

			assert.truthy(b:discard(3));

			assert.equal(8, b:length());

			assert.truthy(b:discard(3));

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

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

		end);

		it("can discard the entire buffer", function ()

			assert.equal(b:len(), 0);

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

			assert.truthy(b:discard(11));

			assert.equal(0, b:len());

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

			assert.truthy(b:discard(12));

			assert.equal(0, b:len());

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

			assert.truthy(b:discard(128));

			assert.equal(0, b:len());

		end);

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

			assert.truthy(dbuffer.new():discard());

			assert.truthy(dbuffer.new():discard(0));

			assert.truthy(dbuffer.new():discard(1));

		end);

	end);

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

		it("works", function ()

			local b = dbuffer.new();

			b:write("hello");

			b:write(" ");

			b:write("world");

			b:collapse(6);

			local ret, bytes = b:read_chunk();

			assert.equal("hello ", ret);

			assert.equal(6, bytes);

		end);

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

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

			assert.truthy(b:discard(3)); -- consume "foo"

			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);

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

			local b = dbuffer.new();

			assert.equal("", b:sub(1, 12));

		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(%s, %s) does not match string:byte()"):format(x and ("%d"):format(x) or "nil", 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);

			test_byte(b, nil, 5);

			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);