package main

import "core:fmt"
import math "core:math"
import hm "core:container/handle_map"
import rl "vendor:raylib"

SQRT2_INV :: 0.7071067811865476

LOG_SIZE :: 8

CollisionPair :: struct {
	a: Handle,
	b: Handle,
}

GameState :: struct {
	player:     Handle,
	camera:     rl.Camera3D,
	entities:   hm.Static_Handle_Map(MAX_ENTITIES, Entity, Handle),
	collisions: [dynamic]CollisionPair,
	log:        [LOG_SIZE]string,
	log_count:  i32,
	kills:      i32,
}

get_entity :: proc(state: ^GameState, h: Handle) -> ^Entity {
	e, ok := hm.get(&state.entities, h)
	return e if ok else nil
}

spawn :: proc(state: ^GameState, e: Entity) -> Handle {
	return hm.add(&state.entities, e)
}

add_log :: proc(state: ^GameState, format: string, args: ..any) {
	msg := fmt.tprintf(format, ..args)
	if state.log_count >= LOG_SIZE {
		for i in 0 ..< LOG_SIZE - 1 {
			state.log[i] = state.log[i + 1]
		}
		state.log[LOG_SIZE - 1] = msg
	} else {
		state.log[state.log_count] = msg
		state.log_count += 1
	}
}

entity_rect :: #force_inline proc(b: ^BaseEntity) -> rl.Rectangle {
	return rl.Rectangle{b.pos.x - b.col_size / 2, b.pos.y - b.col_size / 2, b.col_size, b.col_size}
}

check_col :: proc(a, b: ^BaseEntity) -> (overlap: rl.Rectangle, colliding: bool) {
	c := rl.GetCollisionRec(entity_rect(a), entity_rect(b))
	if c.width <= 0 || c.height <= 0 do return rl.Rectangle{}, false
	return c, true
}

resolve_aabb :: proc(a, b: ^BaseEntity) -> bool {
	c, ok := check_col(a, b)
	if !ok do return false

	if c.width < c.height {
		sign: f32 = 1 if a.pos.x < b.pos.x else -1
		a.pos.x -= sign * c.width * 0.5
		b.pos.x += sign * c.width * 0.5
	} else {
		sign: f32 = 1 if a.pos.y < b.pos.y else -1
		a.pos.y -= sign * c.height * 0.5
		b.pos.y += sign * c.height * 0.5
	}
	return true
}

sys_update :: proc(state: ^GameState, dt: f32) {
	it := hm.iterator_make(&state.entities)
	for e, h in hm.iterate(&it) {
		#partial switch &v in e.v {
		case Player:
			player_update(state, &v, h, dt)
		case Enemy:
			enemy_update(state, &v, h, dt)
		case GroundItem:
			item_update(state, &v, h, dt)
		}
	}

	it2 := hm.iterator_make(&state.entities)
	for e, _ in hm.iterate(&it2) {
		b := get_base(e)
		b.pos += b.vel * dt
	}

	it3 := hm.iterator_make(&state.entities)
	for e, h in hm.iterate(&it3) {
		#partial switch &v in e.v {
		case FX:
			fx_update(state, &v, h, dt)
		case Attack:
			attack_update(state, &v, h, dt)
		}
	}

	resolve_collisions(state)

	apply_collision_effects(state)
}

sys_sweep :: proc(state: ^GameState) {
	it := hm.iterator_make(&state.entities)
	for e, h in hm.iterate(&it) {
		if get_base(e).marked {
			hm.remove(&state.entities, h)
		}
	}
}

entity_draw :: proc(state: ^GameState, e: ^Entity) {
	b := get_base(e)
	sp := rl.GetWorldToScreen({b.pos.x, 0, b.pos.y}, state.camera)
	scale := SCREEN_H / state.camera.fovy

	#partial switch v in b.gfx[0] {
	case GfxCircle:
		rl.DrawCircleV(sp, v.radius * scale, v.color)
	case:
	}
}

ground_effect_draw :: proc(state: ^GameState, e: ^Entity) {
	b := get_base(e)

	#partial switch v in e.v {
	case Attack:
		draw_arc_sector(b.pos, v.dir, v.radius, v.arc, v.color)
	case GroundItem:
		rl.DrawCylinder({b.pos.x, 0.02, b.pos.y}, 8, 8, 0.03, 24, {255, 255, 255, 30})
	case:
	}
}

draw_arc_sector :: proc(pos: rl.Vector2, dir: rl.Vector2, radius: f32, arc: f32, color: rl.Color) {
	SEGMENTS :: 24
	base := math.atan2_f32(dir.y, dir.x)
	start := base - arc * 0.5

	for i in 0 ..< SEGMENTS {
		a1 := start + arc * f32(i) / f32(SEGMENTS)
		a2 := start + arc * f32(i + 1) / f32(SEGMENTS)
		p1 := pos + rl.Vector2{math.cos_f32(a1), math.sin_f32(a1)} * radius
		p2 := pos + rl.Vector2{math.cos_f32(a2), math.sin_f32(a2)} * radius
		rl.DrawTriangle3D(
			{pos.x, 0.03, pos.y},
			{p1.x, 0.03, p1.y},
			{p2.x, 0.03, p2.y},
			color,
		)
	}
}

sys_draw :: proc(state: ^GameState) {
	rl.BeginDrawing()
	rl.ClearBackground({20, 20, 30, 255})

	rl.BeginMode3D(state.camera)
	draw_grid_3d()

	if ray := rl.GetScreenToWorldRay(rl.GetMousePosition(), state.camera); ray.direction.y != 0 {
		t := -ray.position.y / ray.direction.y
		hit := ray.position + ray.direction * t
		rl.DrawCylinder({hit.x, 0.02, hit.z}, 4, 4, 0.02, 16, {255, 255, 255, 90})
	}

	it := hm.iterator_make(&state.entities)
	for e, _ in hm.iterate(&it) {
		ground_effect_draw(state, e)
	}
	rl.EndMode3D()

	scale := SCREEN_H / state.camera.fovy
	it2 := hm.iterator_make(&state.entities)
	for e, _ in hm.iterate(&it2) {
		entity_draw(state, e)
		if a := get_actor(e); a != nil {
			b := get_base(e)
			sp := rl.GetWorldToScreen({b.pos.x, 0, b.pos.y}, state.camera)
			hp_ratio := f32(a.hp) / f32(a.max_hp)
			bar_w := b.col_size * 3 * scale
			bar_pos := sp - rl.Vector2{bar_w / 2, b.col_size * 2 * scale + 12}
			rl.DrawRectangleV(bar_pos, {bar_w, 5}, {60, 60, 60, 255})
			rl.DrawRectangleV(bar_pos, {bar_w * hp_ratio, 5}, {220, 40, 40, 255})
		}
	}

	ui_draw(state)
	rl.EndDrawing()
}

resolve_collisions :: proc(state: ^GameState) {
	clear(&state.collisions)

	hs: [MAX_ENTITIES]Handle
	n := 0
	it := hm.iterator_make(&state.entities)
	for _, h in hm.iterate(&it) {
		hs[n] = h
		n += 1
	}

	for i in 0 ..< n {
		for j in i + 1 ..< n {
			a := get_entity(state, hs[i])
			b := get_entity(state, hs[j])
			if resolve_aabb(get_base(a), get_base(b)) {
				append(&state.collisions, CollisionPair{a = hs[i], b = hs[j]})
			}
		}
	}
}

apply_collision_effects :: proc(state: ^GameState) {
	_, p := get_player(state)

	for c in state.collisions {
		other_h: Handle
		if c.a == state.player {
			other_h = c.b
		} else if c.b == state.player {
			other_h = c.a
		} else do continue

		e := get_entity(state, other_h)
		if e == nil do continue

		#partial switch &v in e.v {
		case Enemy:
			if p != nil && p.invuln_timer <= 0 {
				dmg := v.touch_dmg
				armor: i32 = 0
				if p.equip.armor.kind != .None do armor = p.equip.armor.armor
				dmg = max(dmg - armor / 2, 1)
				p.hp -= dmg
				p.invuln_timer = 0.5
				if p.hp <= 0 do p.hp = 0
			}
		case GroundItem:
			if p != nil && !v.marked && p.inv_count < INV_SIZE {
				p.inventory[p.inv_count] = v.item
				p.inv_count += 1
				v.marked = true
				add_log(state, "Picked up: %s", v.item.name)
			}
		}
	}
}