package assets

import "core:c"
import "core:log"
import "core:math"
import lg "core:math/linalg"
import "game:physics/bvh"
import "libs:tracy"
import rl "vendor:raylib"

Loaded_Texture :: struct {
	texture: rl.Texture2D,
	modtime: c.long,
}

Loaded_Model :: struct {
	model:   rl.Model,
	modtime: c.long,
}

Loaded_BVH :: struct {
	// AABB of all bvhs
	aabb:    bvh.AABB,
	// BVH for each mesh in a model
	bvhs:    []bvh.BVH,
	modtime: c.long,
}

destroy_loaded_bvh :: proc(loaded_bvh: Loaded_BVH) {
	tracy.Zone()

	for &mesh_bvh in loaded_bvh.bvhs {
		bvh.destroy_bvh(&mesh_bvh)
	}
	delete(loaded_bvh.bvhs)
}

Asset_Manager :: struct {
	textures: map[cstring]Loaded_Texture,
	models:   map[cstring]Loaded_Model,
	bvhs:     map[cstring]Loaded_BVH,
}

get_texture :: proc(assetman: ^Asset_Manager, path: cstring) -> rl.Texture2D {
	tracy.Zone()

	modtime := rl.GetFileModTime(path)

	existing, ok := assetman.textures[path]
	if ok && existing.modtime == modtime {
		return existing.texture
	}

	if ok {
		rl.UnloadTexture(existing.texture)
		delete_key(&assetman.textures, path)
		log.infof("deleted texture %s. New textures len: %d", path, len(assetman.textures))
	}

	loaded := rl.LoadTexture(path)
	if rl.IsTextureValid(loaded) {
		assetman.textures[path] = {
			texture = loaded,
			modtime = modtime,
		}
		return loaded
	} else {
		return rl.Texture2D{}
	}
}

get_model_ex :: proc(
	assetman: ^Asset_Manager,
	path: cstring,
	ref_modtime: c.long = 0, // will check reload status using reference load time. When 0 reloaded will be true only if this call triggered reload
) -> (
	model: rl.Model,
	modtime: c.long,
	reloaded: bool,
) {
	tracy.Zone()

	new_modtime := rl.GetFileModTime(path)

	existing, ok := assetman.models[path]
	if ok && existing.modtime == new_modtime {
		return existing.model,
			existing.modtime,
			ref_modtime == 0 ? false : existing.modtime == ref_modtime
	}

	if ok {
		rl.UnloadModel(existing.model)
		delete_key(&assetman.textures, path)
		log.infof("deleted model %s. New models len: %d", path, len(assetman.textures))
	}

	loaded := rl.LoadModel(path)
	if rl.IsModelValid(loaded) {
		assetman.models[path] = {
			model   = loaded,
			modtime = new_modtime,
		}
		return loaded, new_modtime, true
	} else {
		return rl.Model{}, 0, true
	}
}

get_model :: proc(assetman: ^Asset_Manager, path: cstring) -> rl.Model {
	model, _, _ := get_model_ex(assetman, path)

	return model
}

null_bvhs: []bvh.BVH

get_bvh :: proc(assetman: ^Asset_Manager, path: cstring) -> Loaded_BVH {
	tracy.Zone()

	loaded_bvh, ok := assetman.bvhs[path]
	model, modtime, reloaded := get_model_ex(assetman, path, loaded_bvh.modtime)

	should_recreate := reloaded || !ok

	log.debugf(
		"model %v\nmodtime %v\nreloaded %v\nok %v\nshould_recreate %v\nref_modtime %v",
		model,
		modtime,
		reloaded,
		ok,
		should_recreate,
		loaded_bvh.modtime,
	)

	if ok && should_recreate {
		destroy_loaded_bvh(loaded_bvh)
		delete_key(&assetman.bvhs, path)
	}

	if should_recreate {
		new_bvhs := make([]bvh.BVH, model.meshCount)

		outer_aabb := bvh.AABB {
			min = math.F32_MAX,
			max = -math.F32_MAX,
		}

		for i in 0 ..< model.meshCount {
			mesh := model.meshes[i]
			vertices := (cast([^]rl.Vector3)mesh.vertices)[:mesh.vertexCount]
			indices := mesh.indices[:mesh.triangleCount * 3]

			mesh_bvh := bvh.build_bvh_from_mesh(
				{vertices = vertices, indices = indices},
				context.allocator,
			)

			root_aabb := mesh_bvh.bvh.nodes[0].aabb
			outer_aabb.min = lg.min(outer_aabb.min, root_aabb.min)
			outer_aabb.max = lg.max(outer_aabb.max, root_aabb.max)

			new_bvhs[i] = mesh_bvh.bvh
		}

		assetman.bvhs[path] = Loaded_BVH {
			aabb    = outer_aabb,
			bvhs    = new_bvhs,
			modtime = modtime,
		}
	}

	return assetman.bvhs[path]
}

shutdown :: proc(assetman: ^Asset_Manager) {
	tracy.Zone()

	for _, texture in assetman.textures {
		rl.UnloadTexture(texture.texture)
	}
	for _, model in assetman.models {
		rl.UnloadModel(model.model)
	}
	for _, loaded_bvh in assetman.bvhs {
		destroy_loaded_bvh(loaded_bvh)
	}
	delete(assetman.textures)
	delete(assetman.models)
	delete(assetman.bvhs)
}