package sectr

import    "base:runtime"
import  c "core:c/libc"
import    "core:dynlib"
import    "core:mem"
import    "core:mem/virtual"
import    "core:os"
import    "core:slice"
import    "core:strings"
import    "core:time"
import rl "vendor:raylib"

Path_Assets       :: "../assets/"
Path_Input_Replay :: "scratch.sectr_replay"

ModuleAPI :: struct {
	lib         : dynlib.Library,
	write_time  : FileTime,
	lib_version : i32,

	startup     : type_of( startup ),
	shutdown    : type_of( sectr_shutdown ),
	reload      : type_of( reload ),
	tick        : type_of( tick ),
	clean_frame : type_of( clean_frame ),
}

@export
startup :: proc( persistent_mem, frame_mem, transient_mem, files_buffer_mem : ^VArena, host_logger : ^ Logger )
{
	startup_tick := time.tick_now()

	logger_init( & Memory_App.logger, "Sectr", host_logger.file_path, host_logger.file )
	context.logger = to_odin_logger( & Memory_App.logger )

	// Setup memory for the first time
	{
		using Memory_App;
		persistent   = persistent_mem
		frame        = frame_mem
		transient    = transient_mem
		files_buffer = files_buffer_mem

		context.allocator      = persistent_allocator()
		context.temp_allocator = transient_allocator()
		// TODO(Ed) : Put on the transient allocator a slab allocator (transient slab)
	}

	state := new( State, persistent_allocator() )
	using state

	// Setup General Slab
	{
		alignment := uint(mem.DEFAULT_ALIGNMENT)

		policy     : SlabPolicy
		policy_ptr := & policy
		push( policy_ptr, SlabSizeClass {  16 * Megabyte,   4 * Kilobyte, alignment })
		push( policy_ptr, SlabSizeClass {  32 * Megabyte,  16 * Kilobyte, alignment })
		push( policy_ptr, SlabSizeClass {  64 * Megabyte,  32 * Kilobyte, alignment })
		push( policy_ptr, SlabSizeClass {  64 * Megabyte,  64 * Kilobyte, alignment })
		push( policy_ptr, SlabSizeClass {  64 * Megabyte, 128 * Kilobyte, alignment })
		push( policy_ptr, SlabSizeClass {  64 * Megabyte, 256 * Kilobyte, alignment })
		push( policy_ptr, SlabSizeClass {  64 * Megabyte, 512 * Kilobyte, alignment })
		push( policy_ptr, SlabSizeClass {  64 * Megabyte,   1 * Megabyte, alignment })
		push( policy_ptr, SlabSizeClass {  64 * Megabyte,   2 * Megabyte, alignment })
		push( policy_ptr, SlabSizeClass {  64 * Megabyte,   4 * Megabyte, alignment })
		push( policy_ptr, SlabSizeClass {  64 * Megabyte,   8 * Megabyte, alignment })
		push( policy_ptr, SlabSizeClass {  64 * Megabyte,  16 * Megabyte, alignment })
		push( policy_ptr, SlabSizeClass {  64 * Megabyte,  32 * Megabyte, alignment })
		push( policy_ptr, SlabSizeClass { 256 * Megabyte,  64 * Megabyte, alignment })
		push( policy_ptr, SlabSizeClass { 256 * Megabyte, 128 * Megabyte, alignment })
		push( policy_ptr, SlabSizeClass { 512 * Megabyte, 256 * Megabyte, alignment })
		push( policy_ptr, SlabSizeClass { 512 * Megabyte, 512 * Megabyte, alignment })

		alloc_error : AllocatorError
		general_slab, alloc_error = slab_init( policy_ptr, allocator = persistent_allocator() )
		verify( alloc_error == .None, "Failed to allocate the general slab allocator" )
	}

	string_cache = str_cache_init()

	context.user_ptr = state

	input      = & input_data[1]
	input_prev = & input_data[0]

	// Configuration Load
	{
		using config
		resolution_width  = 1000
		resolution_height =  600
		refresh_rate      =    0

		cam_min_zoom                 = 0.25
		cam_max_zoom                 = 10.0
		cam_zoom_mode                = .Smooth
		cam_zoom_smooth_snappiness   = 4.0
		cam_zoom_sensitivity_digital = 0.2
		cam_zoom_sensitivity_smooth  = 4.0

		engine_refresh_hz = 30

		ui_resize_border_width = 10
	}

	Desired_OS_Scheduler_MS :: 1
	sleep_is_granular = set__scheduler_granularity( Desired_OS_Scheduler_MS )

	// rl.Odin_SetMalloc( RL_MALLOC )

	rl.SetConfigFlags( {
		rl.ConfigFlag.WINDOW_RESIZABLE,
		rl.ConfigFlag.WINDOW_TOPMOST,
	})

	// Rough setup of window with rl stuff
	window_width  : i32 = 1000
	window_height : i32 = 600
	win_title     : cstring = "Sectr Prototype"
	rl.InitWindow( window_width, window_height, win_title )
	log( "Raylib initialized and window opened" )

	window := & state.app_window
	window.extent.x = f32(window_width)  * 0.5
	window.extent.y = f32(window_height) * 0.5

	// We do not support non-uniform DPI.
	window.dpi_scale = rl.GetWindowScaleDPI().x
	window.ppcm      = os_default_ppcm * window.dpi_scale

	// Determining current monitor and setting the target frametime based on it..
	monitor_id         = rl.GetCurrentMonitor()
	monitor_refresh_hz = rl.GetMonitorRefreshRate( monitor_id )
	rl.SetTargetFPS( 60 * 24 )
	log( str_fmt_tmp( "Set target FPS to: %v", monitor_refresh_hz ) )

	// Basic Font Setup
	{
		font_provider_startup()
		// path_rec_mono_semicasual_reg := strings.concatenate( { Path_Assets, "RecMonoSemicasual-Regular-1.084.ttf" })
		// font_rec_mono_semicasual_reg  = font_load( path_rec_mono_semicasual_reg, 24.0, "RecMonoSemiCasual_Regular" )

		// path_squidgy_slimes := strings.concatenate( { Path_Assets, "Squidgy Slimes.ttf" } )
		// font_squidgy_slimes = font_load( path_squidgy_slimes, 24.0, "Squidgy_Slime" )

		path_firacode := strings.concatenate( { Path_Assets, "FiraCode-Regular.ttf" }, transient_allocator() )
		font_firacode  = font_load( path_firacode, 24.0, "FiraCode" )
		default_font = font_firacode
		log( "Default font loaded" )
	}

	// Demo project setup
	{
		using project
		path           = str_intern("./")
		name           = str_intern( "First Project" )
		workspace.name = str_intern( "First Workspace" )
		{
			using project.workspace
			cam = {
				target   = { 0, 0 },
				offset   = transmute(Vec2) window.extent,
				rotation = 0,
				zoom     = 1.0,
			}
			// cam = {
			// 	position   = { 0, 0, -100 },
			// 	target     = { 0, 0, 0 },
			// 	up         = { 0, 1, 0 },
			// 	fovy       = 90,
			// 	projection = rl.CameraProjection.ORTHOGRAPHIC,
			// }

			// Setup workspace UI state
			ui_startup( & workspace.ui, cache_allocator =  general_slab_allocator() )
		}
	}

	startup_ms := duration_ms( time.tick_lap_time( & startup_tick))
	log( str_fmt_tmp("Startup time: %v ms", startup_ms) )

	// Make sure to cleanup transient before continuing...
	// From here on, tarnsinet usage has to be done with care.
	// For most cases, the frame allocator should be more than enough.
	free_all( transient_allocator() )
}

// For some reason odin's symbols conflict with native foreign symbols...
@export
sectr_shutdown :: proc()
{
	if Memory_App.persistent == nil {
		return
	}
	state := get_state()

	// Replay
	{
		file_close( Memory_App.replay.active_file )
	}

	font_provider_shutdown()

	log("Module shutdown complete")
}

@export
reload :: proc( persistent_mem, frame_mem, transient_mem, files_buffer_mem : ^VArena, host_logger : ^ Logger )
{
	using Memory_App;

	persistent   = persistent_mem
	frame        = frame_mem
	transient    = transient_mem
	files_buffer = files_buffer_mem

	context.allocator      = persistent_allocator()
	context.temp_allocator = transient_allocator()

	// Procedure Addresses are not preserved on hot-reload. They must be restored for persistent data.
	// The only way to alleviate this is to either do custom handles to allocators
	// Or as done below, correct containers using allocators on reload.
	// Thankfully persistent dynamic allocations are rare, and thus we know exactly which ones they are.

	font_provider_data := & get_state().font_provider_data
	font_provider_data.font_cache.hashes.allocator  = general_slab_allocator()
	font_provider_data.font_cache.entries.allocator = general_slab_allocator()

	ui_reload( & get_state().project.workspace.ui, cache_allocator =  general_slab_allocator() )

	log("Module reloaded")
}

// TODO(Ed) : This lang really not have a fucking swap?
swap :: proc( a, b : ^ $Type ) -> ( ^ Type, ^ Type ) {
	return b, a
}

@export
tick :: proc( host_delta_time : f64, host_delta_ns : Duration ) -> b32
{
	client_tick := time.tick_now()

	context.allocator      = frame_allocator()
	context.temp_allocator = transient_allocator()
	state := get_state(); using state

	rl.PollInputEvents()

	result := update( host_delta_time )
	render()

	rl.SwapScreenBuffer()

	config.engine_refresh_hz = uint(monitor_refresh_hz)
	frametime_target_ms          = 1.0 / f64(config.engine_refresh_hz) * S_To_MS
	sub_ms_granularity_required := frametime_target_ms <= Frametime_High_Perf_Threshold_MS

	frametime_delta_ns      = time.tick_lap_time( & client_tick )
	frametime_delta_ms      = duration_ms( frametime_delta_ns )
	frametime_delta_seconds = duration_seconds( frametime_delta_ns )
	frametime_elapsed_ms    = frametime_delta_ms + host_delta_time

	if frametime_elapsed_ms < frametime_target_ms
	{
		sleep_ms       := frametime_target_ms - frametime_elapsed_ms
		pre_sleep_tick := time.tick_now()

		if sleep_ms > 0 {
			thread_sleep( cast(Duration) sleep_ms * MS_To_NS )
			// thread__highres_wait( sleep_ms )
		}

		sleep_delta_ns := time.tick_lap_time( & pre_sleep_tick)
		sleep_delta_ms := duration_ms( sleep_delta_ns )

		if sleep_delta_ms < sleep_ms {
			// log( str_fmt_tmp("frametime sleep was off by: %v ms", sleep_delta_ms - sleep_ms ))
		}

		frametime_elapsed_ms += sleep_delta_ms
		for ; frametime_elapsed_ms < frametime_target_ms; {
			sleep_delta_ns = time.tick_lap_time( & pre_sleep_tick)
			sleep_delta_ms = duration_ms( sleep_delta_ns )

			frametime_elapsed_ms += sleep_delta_ms
		}
	}

	if frametime_elapsed_ms > 60.0 {
		log( str_fmt_tmp("Big tick! %v ms", frametime_elapsed_ms), LogLevel.Warning )
	}

	return result
}

@export
clean_frame :: proc() {
	free_all( frame_allocator() )
}