package edit2d

import "core:strings"
import "core:os"
import "core:bytes"
import "core:path/filepath"
import "core:crypto/hash"
import "core:time"
import b2 "vendor:box2d"
import "core:fmt"
import "core:encoding/cbor"
import draw "./draw"

/*
	The engine can provide helper functions so that it'll be easier to write 
	the level code in the game 

	A Typical level code
*/

Engine_World :: struct {
	world_id : b2.WorldId,
	
	//This in engine code?
	static_indexes          : map[Static_Index]int `cbor:"-"`,
	relations               : map[^Static_Index][dynamic]Static_Index_Global `cbor:"-"`,
	relations_serializeable : map[ Static_Index][dynamic]Static_Index_Global,

	
	/*
		Seems okay to put the joint defs in engine rather than in game because
		we don't add more attributes in joints in the game

		Can be changed later without requireing refactor
	*/
	revolute_joint_defs     : [dynamic]revolt_joint_def,
	distant_joint_defs      : [dynamic]distance_joint_def,
	joints                  : [dynamic]b2.JointId `cbor:"-"`,
	cam                     : draw.Camera,
	name                    : string,
}

@(require_results)
time_to_string_hms :: proc(t: time.Time, buf: []u8) -> (res: string) #no_bounds_check {
	assert(len(buf) >= time.MIN_HMS_LEN)
	h, m, s := time.clock(t)

	buf[7] = '0' + u8(s % 10); s /= 10
	buf[6] = '0' + u8(s)
	buf[5] = '-'
	buf[4] = '0' + u8(m % 10); m /= 10
	buf[3] = '0' + u8(m)
	buf[2] = '-'
	buf[1] = '0' + u8(h % 10); h /= 10
	buf[0] = '0' + u8(h)

	return string(buf[:time.MIN_HMS_LEN])
}

cbor_flags : cbor.Encoder_Flags : 
{
	.Self_Described_CBOR, 
	.Deterministic_Int_Size, 
	.Deterministic_Float_Size, 
}

level_load_from_files :: proc(
	$G, $L, $E: typeid, 
	game: ^G,
	state: ^Engine_State
	)
{
	files, err := os.read_all_directory_by_path("levels", context.allocator)
	
	for file in files 
	{
		if !os.exists(file.fullpath) do continue
		if os.is_dir(file.fullpath) do continue

		level_name := strings.clone(filepath.stem(file.fullpath))
		game.levels[level_name] = {}
		game.curr_level = strings.clone(level_name)
		level_init_from_path(L, E, &game.levels[level_name], file.fullpath, state)
	}
}


//Returns engine_world by reading from the file


/*
	In the user code

	level_name = strings.clone(filepath.stem(path))
	game.levels[level_name] = {}

	level_init_from_path(&game.levels[level_name], path)

*/
//We don't want the user to configure and use cbor everytime so we want to handle it
//
level_init_from_path :: proc(
	$T, $E: typeid,
	level_data : ^T,
	path : string, 
	state: ^Engine_State,
	) -> (ret : bool)
{

	level := cast(^Engine_World)level_data

	if os.is_file(path)
	{

		level_name     := strings.clone(filepath.stem(path))
		data, err      := os.read_entire_file_from_path(path, context.allocator)
		level.name      = level_name

		//?
		level.relations = {}
		level.relations = make(map[^Static_Index][dynamic]Static_Index_Global)

		if len(data) > 0
		{

			unmarshall_err := cbor.unmarshal(data, level_data)
			delete(data)

			if unmarshall_err == nil
			{

				level_reload(T, E, level_data)
				state.draw.cam = level.cam

				for key, val in level.relations_serializeable
				{
					index  := level.static_indexes[key]
					entity := level_data.entities[index]

					level_data.relations[entity.index] = {}
					for v in val do append(&level.relations[entity.index], v)
				}

				ret = true
			}else
			{
				ret = false
				fmt.eprintf("Faield to unmarshall file %s \n", unmarshall_err)
			}

		}else
		{
			level_reload(T, E, level_data)
			state.draw.cam = level.cam

			for key, val in level.relations_serializeable
			{
				index  := level.static_indexes[key]
				entity := level_data.entities[index]

				level_data.relations[entity.index] = {}
				for v in val do append(&level.relations[entity.index], v)
			}

			//Handle no data
			fmt.println("Empty level")
			ret = false
		}

	}else
	{
		fmt.eprintln("File not exist or is a directory")
		ret = false
	}

	return 
}

/*
	We can't create the entities
	That should be done by the user
*/
level_reload :: proc($T: typeid, $E: typeid, level: ^T)
{
	clear(&level.entities)
	clear(&level.static_indexes)

	if level.world_id != b2.nullWorldId do b2.DestroyWorld(level.world_id)

	//initilize world
	{
		world_def    := b2.DefaultWorldDef()
		b2.SetLengthUnitsPerMeter(100)

		//Get the gravity from config
		world_def.gravity = {0, -9.8 * 100}
		level.world_id    = b2.CreateWorld(world_def)
	}

	for &def, i in &level.entity_defs
	{
		//new_entity := engine_create_entity(&def, level.world_id, i32(i))
		new_entity : E
		new_entity.type   = def.type
		new_entity.engine = engine_create_entity(&def, level.world_id, i32(i))

		//new_entity := entity_create_by_type(&def, level.world_id, i32(i))
		
		append(&level.entities, new_entity)
		
		if new_entity.index != nil do level.static_indexes[new_entity.index^] = i

		//if new_entity.type  == .PLAYER do level.player_index = i32(i)

	}

	{
		for &def in &level.distant_joint_defs
		{
			//Get entity_a and entity_b

			if def.entity_a <= 0 do continue
			if def.entity_b <= 0 do continue

			entity_a   := &level.entities[level.static_indexes[def.entity_a]]
			def.bodyIdA = entity_a.body_id

			entity_b   := &level.entities[level.static_indexes[def.entity_b]]
			def.bodyIdB = entity_b.body_id

			append(&level.joints, b2.CreateDistanceJoint(level.world_id, def.def))
		}

		for &def in &level.revolute_joint_defs
		{
			//Get entity_a and entity_b

			if def.entity_a <= 0 do continue
			if def.entity_b <= 0 do continue

			entity_a   := &level.entities[level.static_indexes[def.entity_a]]
			def.bodyIdA = entity_a.body_id

			entity_b   := &level.entities[level.static_indexes[def.entity_b]]
			def.bodyIdB = entity_b.body_id

			append(&level.joints, b2.CreateRevoluteJoint(level.world_id, def.def))
		}
	}
	//level.player.e = &level.entities[level.player_index]
}


/*
	Saves the level to the levels directory using level's name as filename
	It uses core library's hash and cbor to searialize the level into bytes

	It assumes that it uses engine_world struct as it's first member

	Checks hash of current level state and file's hash
	If both hash is same the exits
*/

level_save_to_file :: proc(level_data: ^$T, state: ^Engine_State)
{

	level      := cast(^Engine_World)level_data
	level_path := fmt.tprintf("levels/%s.cbor", level.name)

	level.cam = state.draw.cam
	fmt.println(level_path)

	//Relation serializeable
	{
		clear(&level.relations_serializeable)
		for key, val in &level.relations
		{
			if key != nil
			{
				level.relations_serializeable[key^] = {}
				for v in val do append(&level.relations_serializeable[key^], v)
			}
		}
	}

	binary, cbor_err := cbor.marshal_into_bytes(level_data^, cbor_flags)

	if cbor_err == nil
	{
	}else
	{
		fmt.eprintf("Failed to marshall level %s \n", cbor_err)
		return
	}


	//Get hash of current loaded game and current saved game
	binary_hash         := hash.hash_bytes(.SHA3_512, binary)
	fmt.println(binary_hash)
	file_hash, hash_err := hash.hash_file_by_name(.SHA3_512, level_path)

	//If the hash is same that means no changes has been made


	if bytes.compare(binary_hash, file_hash) != 0
	{

		if !os.exists("levels")
		{
			err := os.mkdir("levels")
			if err != nil
			{
				fmt.println("Failed to create levels directory")
				fmt.println(err)
			}
		}

		/* 
			Create backeup before saving to file

			We create backup by copying the current level file to the backup directory
			Backup directory will contain the date and time of the backup
		*/


		if os.exists(level_path)
		{
			//Get time and date to create file and folder name for backup
			curr_time := time.now()

			buf      : [time.MIN_YYYY_DATE_LEN]u8
			time_buf : [time.MIN_HMS_LEN]u8
			date_str := time.to_string_yyyy_mm_dd(curr_time, buf[:])
			time_str := time_to_string_hms(curr_time, time_buf[:])

			backup_dir_path  := fmt.tprintf("levels/backups/%s",date_str)
			backup_file_path := fmt.tprintf("levels/backups/%s/%s-%s", date_str, level.name, time_str)
		
			bk_err := os.make_directory_all(backup_dir_path)

			if bk_err != nil
			{
				fmt.eprintf("Failed to create backup directory %s \n", bk_err)
			}
			else{
				bk_err := os.copy_file(backup_file_path, level_path)

				if bk_err != nil
				{
					fmt.eprintf("Failed to copy file %s\n", bk_err)
				}
			}
		}

		//Save the current binary to file
		save_err := os.write_entire_file_from_bytes(level_path, binary)

		if save_err != nil
		{
			fmt.eprintf("Failed to save level %s\n", save_err)
		}
	

	}else{
		fmt.println("No changes detected")
	}
}


/*
	The engine assumes that it has attribute entities
*/
game_to_engine_entities :: proc($Game: typeid, game_data: ^Game, state: ^Engine_State)
{
	level     := &game_data.levels[game_data.curr_level]

	interface : ^Interface_State = &game_data.interface

	clear(&interface.entities)
	clear(&interface.entity_defs)

	for &entity in &level.entities    
	{
		append(&interface.entities,    &entity.engine)
	}
	for &def    in &level.entity_defs 
	{
		append(&interface.entity_defs, &def.engine)
	}

	interface.state = state
	interface.world = &level.engine
}