local gl = honey.gl
local window = honey.window

gl.errorName = function(errorCode)
	for name, code in pairs(gl.errorType) do
		if code == errorCode then return name end
	end
	return 'unknown'
end

gl.init()
window.setHint(window.hintType.contextVersionMajor, 3)
window.setHint(window.hintType.contextVersionMinor, 3)
window.setHint(window.hintType.openGlProfile, window.profileType.openGlCoreProfile)

local w = window.create(640, 480, 'hello, world!')
window.makeContextCurrent(w)
gl.initGlad()

window.setFramebufferSizeCallback(w, function(_, width, height)
	print(string.format("resize: (%d, %d)", width, height))
	gl.setViewport(0, 0, width, height)
end)


local vertexShaderSource = [[
#version 330 core
layout (location = 0) in vec3 aPos;
out vec3 pos;

void main()
{
    gl_Position = vec4(aPos.x, aPos.y, aPos.z, 1.0);
    pos = aPos;
}
]]

local fragmentShaderSource = [[
#version 330 core
in vec3 pos;
out vec4 FragColor;

void main()
{
	FragColor = vec4(pos.x+0.5, 0.0f, 2*(pos.y+pos.x), 1.0f);
}
]]

local vertexShader = gl.shader.create(gl.shader.type.vertexShader)
gl.shader.setSource(vertexShader, vertexShaderSource)
gl.shader.compile(vertexShader)
local fragmentShader = gl.shader.create(gl.shader.type.fragmentShader)
gl.shader.setSource(fragmentShader, fragmentShaderSource)
gl.shader.compile(fragmentShader)

local shader = gl.shader.createProgram()
gl.shader.attachShader(shader, vertexShader)
gl.shader.attachShader(shader, fragmentShader)
gl.shader.link(shader)
gl.shader.delete(vertexShader)
gl.shader.delete(fragmentShader)


local vertices = {
    -0.5, -0.5, 0.0,
     0.5, -0.5, 0.0,
     0.0,  0.5, 0.0
}  

local vertexArray = gl.data.createVertexArray()

local vertexBuffer = gl.data.createBuffer()
gl.data.bindVertexArray(vertexArray)

gl.data.bindBuffer(gl.data.bufferTarget.arrayBuffer, vertexBuffer)
local err = gl.getError()
if err ~= gl.errorType.noError then error(gl.errorName(err)) end
gl.data.bufferData(gl.data.bufferTarget.arrayBuffer, gl.dataType.float, vertices, gl.data.bufferUsage.staticDraw)
if gl.getError() ~= gl.errorType.noError then error(gl.getError()) end

gl.data.vertexAttribPointer(0, 3, false, 3, 0)
if gl.getError() ~= gl.errorType.noError then error(gl.getError()) end
gl.data.vertexArrayEnableAttrib(0)
if gl.getError() ~= gl.errorType.noError then error(gl.getError()) end

gl.data.bindBuffer(gl.data.bufferTarget.arrayBuffer, 0)
if gl.getError() ~= gl.errorType.noError then error(gl.getError()) end

while not window.shouldClose(w) do
	gl.draw.setClearColor(0.2, 0.3, 0.3, 1.0)
	gl.draw.clear(gl.draw.bufferMask.colorBuffer);

	gl.shader.use(shader)
	gl.data.bindVertexArray(vertexArray)
	gl.draw.drawArrays(gl.draw.primitiveType.triangles, 0, 3)

	window.swapBuffers(w)
	window.pollEvents()
end
window.destroy(w)
gl.terminate()