Ime

-- To run this sample:
-- bin/soluna.exe entry=test/ime.lua

local soluna = require "soluna"
local app = require "soluna.app"
local mattext = require "soluna.material.text"
local matquad = require "soluna.material.quad"
local matmask = require "soluna.material.mask"
local font = require "soluna.font"
local file = require "soluna.file"
local utf8 = utf8
local math = math
local string = string
local table = table

local args = ...
local batch = assert(args.batch)

local KEY_LEFT <const> = 263
local KEY_RIGHT <const> = 262
local KEY_HOME <const> = 268
local KEY_END <const> = 269
local KEY_BACKSPACE <const> = 259
local KEY_DEL <const> = 261
local KEY_ENTER <const> = 257
local KEYSTATE_PRESS <const> = 1
local CHAR_BACKSPACE <const> = 8
local CHAR_DELETE <const> = 127

local FONT_SIZE <const> = 32
local HELP_SIZE <const> = 18
local BOX_WIDTH <const> = 720
local BOX_HEIGHT <const> = 84
local BOX_PADDING_X <const> = 18
local BOX_PADDING_Y <const> = 8
local BOX_RADIUS <const> = 10
local CURSOR_BLINK <const> = 30

local function load_font()
	if soluna.platform == "wasm" then
		local bundled_name = "Source Han Sans SC Regular"
		local bundled_path = "asset/font/SourceHanSansSC-Regular.ttf"
		local bundled_data = file.load(bundled_path)
		if bundled_data then
			font.import(bundled_data)
			local bundled_id = font.name(bundled_name)
			if bundled_id then
				return bundled_id, bundled_name
			end
		end
	end

	local sysfont = require "soluna.font.system"
	local candidates = {
		"WenQuanYi Micro Hei",  -- Linux
		"Microsoft YaHei",      -- Windows
		"Yuanti SC",            -- macOS
		"Source Han Sans SC Regular", -- WASM
	}
	for _, name in ipairs(candidates) do
		local ok, data = pcall(sysfont.ttfdata, name)
		if ok and data then
			font.import(data)
			local fontid = font.name(name)
			if fontid then
				return fontid, name
			end
		end
	end
	error "No available system font for IME sample"
end

local function cache(f)
	return setmetatable({}, {
		__index = function(self, k)
			local v = f(k)
			self[k] = v
			return v
		end
	})
end

local quad_cache = cache(function(key)
	local w, h, c = key:match "^(%-?%d+):(%-?%d+):(%x+)$"
	return matquad.quad(tonumber(w), tonumber(h), tonumber(c, 16))
end)

local function cached_quad(w, h, c)
	local key = string.format("%d:%d:%08x", w, h, c)
	return quad_cache[key]
end

local mask_cache = cache(function(key)
	local sprite, color = key:match "^(%d+):(%x+)$"
	return matmask.mask(tonumber(sprite), tonumber(color, 16))
end)

local function cached_mask(sprite, color)
	local key = string.format("%d:%08x", sprite, color)
	return mask_cache[key]
end

local function clamp(v, lo, hi)
	if v < lo then
		return lo
	elseif v > hi then
		return hi
	end
	return v
end

local function rounded_box_rgba(w, h, radius)
	local r = math.floor(clamp(radius, 0, math.min(w, h) * 0.5))
	local edge = r * r
	local left = r
	local right = w - r
	local top = r
	local bottom = h - r
	local opaque = "\255\255\255\255"
	local transparent = "\255\255\255\0"
	local lines = {}
	for y = 0, h - 1 do
		local py = y + 0.5
		local row = {}
		for x = 0, w - 1 do
			local px = x + 0.5
			local qx = clamp(px, left, right)
			local qy = clamp(py, top, bottom)
			local dx = px - qx
			local dy = py - qy
			row[x + 1] = (dx * dx + dy * dy <= edge) and opaque or transparent
		end
		lines[y + 1] = table.concat(row)
	end
	return table.concat(lines)
end

local rounded_box_cache = {}

local function rounded_box_sprite(w, h, radius)
	local key = string.format("%d:%d:%d", w, h, radius)
	local sprite = rounded_box_cache[key]
	if sprite then
		return sprite
	end
	local filename = "@" .. "ime_round_" .. key:gsub(":", "_")
	soluna.preload {
		filename = filename,
		content = rounded_box_rgba(w, h, radius),
		w = w,
		h = h,
	}
	local sprites = soluna.load_sprites {
		{
			name = "box",
			filename = filename,
			cw = w,
			ch = h,
			x = 0,
			y = 0,
		}
	}
	rounded_box_cache[key] = sprites.box
	return sprites.box
end

local fontid, font_name = load_font()
local fontcobj = font.cobj()
local text_block, text_cursor = mattext.block(fontcobj, fontid, FONT_SIZE, 0x000000, "LV")
local help_block = mattext.block(fontcobj, fontid, HELP_SIZE, 0x222222, "LV")

soluna.set_window_title "soluna ime sample"
app.set_ime_font(font_name, FONT_SIZE)

local state = {
	screen_w = args.width,
	screen_h = args.height,
	mouse_x = 0,
	mouse_y = 0,
	focused = true,
	caret_tick = 0,
	text = "",
	cursor = 0,
	suppress_control_char = nil,
}

local function char_count(s)
	return utf8.len(s) or 0
end

local function clamp_cursor()
	local n = char_count(state.text)
	if state.cursor < 0 then
		state.cursor = 0
	elseif state.cursor > n then
		state.cursor = n
	end
end

local function byte_offset_for_char(index_1based)
	return utf8.offset(state.text, index_1based) or (#state.text + 1)
end

local function insert_text(s)
	if not s or s == "" then
		return
	end
	local byte = byte_offset_for_char(state.cursor + 1)
	state.text = state.text:sub(1, byte - 1) .. s .. state.text:sub(byte)
	state.cursor = state.cursor + char_count(s)
end

local function delete_backward()
	if state.cursor <= 0 then
		return
	end
	local from = byte_offset_for_char(state.cursor)
	local to = byte_offset_for_char(state.cursor + 1)
	state.text = state.text:sub(1, from - 1) .. state.text:sub(to)
	state.cursor = state.cursor - 1
end

local function delete_forward()
	local n = char_count(state.text)
	if state.cursor >= n then
		return
	end
	local from = byte_offset_for_char(state.cursor + 1)
	local to = byte_offset_for_char(state.cursor + 2)
	state.text = state.text:sub(1, from - 1) .. state.text:sub(to)
end

local function is_control_char(codepoint)
	return codepoint < 32 or (codepoint >= 127 and codepoint <= 159)
end

local function handle_control_delete(codepoint)
	if codepoint ~= CHAR_BACKSPACE and codepoint ~= CHAR_DELETE then
		return
	end
	if state.suppress_control_char == codepoint then
		state.suppress_control_char = nil
		return
	end
	state.suppress_control_char = nil
	if codepoint == CHAR_BACKSPACE then
		delete_backward()
	else
		delete_forward()
	end
end

local function decode_char_event(value)
	local t = type(value)
	if t == "number" then
		if is_control_char(value) then
			return nil, value
		end
		return utf8.char(value), nil
	end
	if t ~= "string" or value == "" then
		return nil, nil
	end
	local first = utf8.codepoint(value, 1, 1)
	if first and is_control_char(first) then
		return nil, first
	end
	return value, nil
end

local function box_rect()
	local w = math.min(BOX_WIDTH, math.max(320, state.screen_w - 48))
	local h = BOX_HEIGHT
	local x = (state.screen_w - w) // 2
	local y = (state.screen_h - h) // 2
	return x, y, w, h
end

local function in_box(x, y, bx, by, bw, bh)
	return x >= bx and x <= bx + bw and y >= by and y <= by + bh
end

local callback = {}

function callback.window_resize(w, h)
	state.screen_w = w
	state.screen_h = h
end

function callback.mouse_move(x, y)
	state.mouse_x = x
	state.mouse_y = y
end

function callback.mouse_button(button, key_state)
	if button ~= 0 or key_state ~= KEYSTATE_PRESS then
		return
	end
	local bx, by, bw, bh = box_rect()
	state.focused = in_box(state.mouse_x, state.mouse_y, bx, by, bw, bh)
	if not state.focused then
		app.set_ime_rect(nil)
	end
end

function callback.char(value)
	if not state.focused then
		return
	end
	local text_input, control = decode_char_event(value)
	if control then
		handle_control_delete(control)
		return
	end
	if not text_input then
		return
	end
	insert_text(text_input)
	clamp_cursor()
	state.caret_tick = 0
end

function callback.key(keycode, key_state)
	if key_state ~= KEYSTATE_PRESS or not state.focused then
		return
	end
	if keycode == KEY_LEFT then
		state.cursor = state.cursor - 1
	elseif keycode == KEY_RIGHT then
		state.cursor = state.cursor + 1
	elseif keycode == KEY_HOME then
		state.cursor = 0
	elseif keycode == KEY_END then
		state.cursor = char_count(state.text)
	elseif keycode == KEY_BACKSPACE then
		delete_backward()
		state.suppress_control_char = CHAR_BACKSPACE
	elseif keycode == KEY_DEL then
		delete_forward()
		state.suppress_control_char = CHAR_DELETE
	elseif keycode == KEY_ENTER then
		insert_text "\n"
	end
	clamp_cursor()
	state.caret_tick = 0
end

function callback.frame()
	clamp_cursor()
	local bx, by, bw, bh = box_rect()
	local box_sprite = rounded_box_sprite(bw, bh, BOX_RADIUS)
	local tx = bx + BOX_PADDING_X
	local ty = by + BOX_PADDING_Y
	local tw = bw - BOX_PADDING_X * 2
	local th = bh - BOX_PADDING_Y * 2

	batch:add(cached_quad(state.screen_w, state.screen_h, 0xf2f2f2ff), 0, 0)
	batch:add(cached_mask(box_sprite, state.focused and 0xffffffff or 0xe8e8e8ff), bx, by)
	batch:add(
		cached_quad(
			math.max(bw - BOX_RADIUS * 2, 2),
			2,
			state.focused and 0x1d6ef0ff or 0x9a9a9aff
		),
		bx + BOX_RADIUS,
		by + bh - 2
	)

	local label = text_block(state.text, tw, th)
	batch:add(label, tx, ty)

	local cx, cy, cw, ch, n, descent = text_cursor(state.text, state.cursor, tw, th)
	state.cursor = n
	descent = descent or 0
	if state.focused then
		app.set_ime_rect {
			x = tx + cx,
			y = ty + cy - descent,
			width = cw,
			height = ch,
			text_color = 0xff000000,
		}
	else
		app.set_ime_rect(nil)
	end

	state.caret_tick = (state.caret_tick + 1) % (CURSOR_BLINK * 2)
	if state.focused and state.caret_tick < CURSOR_BLINK then
		batch:add(cached_quad(math.max(cw, 2), ch, 0x111111ff), tx + cx, ty + cy)
	end

	local help = help_block("Click box, type with CJK.", state.screen_w - 32, 24)
	batch:add(help, 16, 16)
end

return callback