// Copyright (c) 2019-2023 Alexander Medvednikov. All rights reserved.
// Use of this source code is governed by an MIT license that can be found in the LICENSE file.
module gg

import fontstash
import sokol.sfons
import sokol.sgl
import gx
import os
import os.font

struct FT {
pub:
	fons        &fontstash.Context = unsafe { nil }
	font_normal int
	font_bold   int
	font_mono   int
	font_italic int
	scale       f32 = 1.0
}

fn new_ft(c FTConfig) ?&FT {
	if c.font_path == '' {
		if c.bytes_normal.len > 0 {
			fons := sfons.create(512, 512, 1)
			bytes_normal := c.bytes_normal
			bytes_bold := if c.bytes_bold.len > 0 {
				c.bytes_bold
			} else {
				debug_font_println('setting bold variant to normal')
				bytes_normal
			}
			bytes_mono := if c.bytes_mono.len > 0 {
				c.bytes_mono
			} else {
				debug_font_println('setting mono variant to normal')
				bytes_normal
			}
			bytes_italic := if c.bytes_italic.len > 0 {
				c.bytes_italic
			} else {
				debug_font_println('setting italic variant to normal')
				bytes_normal
			}

			return &FT{
				fons: fons
				font_normal: fons.add_font_mem('sans', bytes_normal, false)
				font_bold: fons.add_font_mem('sans', bytes_bold, false)
				font_mono: fons.add_font_mem('sans', bytes_mono, false)
				font_italic: fons.add_font_mem('sans', bytes_italic, false)
				scale: c.scale
			}
		} else {
			// Load default font
		}
	}

	if c.font_path == '' || !os.exists(c.font_path) {
		$if !android {
			println('failed to load font "${c.font_path}"')
			return none
		}
	}

	mut normal_path := c.font_path
	mut bytes := []u8{}
	$if android {
		// First try any filesystem paths
		bytes = os.read_bytes(c.font_path) or { []u8{} }
		if bytes.len == 0 {
			// ... then try the APK asset path
			bytes = os.read_apk_asset(c.font_path) or {
				println('failed to load font "${c.font_path}"')
				return none
			}
		}
	} $else {
		bytes = os.read_bytes(c.font_path) or {
			println('failed to load font "${c.font_path}"')
			return none
		}
	}
	mut bold_path := if c.custom_bold_font_path != '' {
		c.custom_bold_font_path
	} else {
		font.get_path_variant(c.font_path, .bold)
	}
	bytes_bold := os.read_bytes(bold_path) or {
		debug_font_println('failed to load font "${bold_path}"')
		bold_path = c.font_path
		bytes
	}
	mut mono_path := font.get_path_variant(c.font_path, .mono)
	bytes_mono := os.read_bytes(mono_path) or {
		debug_font_println('failed to load font "${mono_path}"')
		mono_path = c.font_path
		bytes
	}
	mut italic_path := font.get_path_variant(c.font_path, .italic)
	bytes_italic := os.read_bytes(italic_path) or {
		debug_font_println('failed to load font "${italic_path}"')
		italic_path = c.font_path
		bytes
	}
	fons := sfons.create(512, 512, 1)
	debug_font_println('Font used for font_normal : ${normal_path}')
	debug_font_println('Font used for font_bold   : ${bold_path}')
	debug_font_println('Font used for font_mono   : ${mono_path}')
	debug_font_println('Font used for font_italic : ${italic_path}')
	return &FT{
		fons: fons
		font_normal: fons.add_font_mem('sans', bytes, false)
		font_bold: fons.add_font_mem('sans', bytes_bold, false)
		font_mono: fons.add_font_mem('sans', bytes_mono, false)
		font_italic: fons.add_font_mem('sans', bytes_italic, false)
		scale: c.scale
	}
}

// set_text_cfg sets the current text configuration
pub fn (ctx &Context) set_text_cfg(cfg gx.TextCfg) {
	if !ctx.font_inited {
		return
	}
	if cfg.bold {
		ctx.ft.fons.set_font(ctx.ft.font_bold)
	} else if cfg.mono {
		ctx.ft.fons.set_font(ctx.ft.font_mono)
	} else if cfg.italic {
		ctx.ft.fons.set_font(ctx.ft.font_italic)
	} else {
		ctx.ft.fons.set_font(ctx.ft.font_normal)
	}
	scale := if ctx.ft.scale == 0 { f32(1) } else { ctx.ft.scale }
	size := if cfg.mono { cfg.size - 2 } else { cfg.size }
	ctx.ft.fons.set_size(scale * f32(size))
	ctx.ft.fons.set_align(int(cfg.align) | int(cfg.vertical_align))
	color := sfons.rgba(cfg.color.r, cfg.color.g, cfg.color.b, cfg.color.a)
	if cfg.color.a != 255 {
		sgl.load_pipeline(ctx.pipeline.alpha)
	}
	ctx.ft.fons.set_color(color)
	ascender := f32(0.0)
	descender := f32(0.0)
	lh := f32(0.0)
	ctx.ft.fons.vert_metrics(&ascender, &descender, &lh)
}

// draw_text draws the string in `text_` starting at top-left position `x`,`y`.
// Text settings can be provided with `cfg`.
pub fn (ctx &Context) draw_text(x int, y int, text_ string, cfg gx.TextCfg) {
	$if macos {
		if ctx.native_rendering {
			if cfg.align == gx.align_right {
				width := ctx.text_width(text_)
				C.darwin_draw_string(x - width, ctx.height - y, text_, cfg)
			} else {
				C.darwin_draw_string(x, ctx.height - y, text_, cfg)
			}
			return
		}
	}
	if !ctx.font_inited {
		eprintln('gg: draw_text(): font not initialized')
		return
	}
	// text := text_.trim_space() // TODO remove/optimize
	// mut text := text_
	// if text.contains('\t') {
	// text = text.replace('\t', '    ')
	// }
	ctx.set_text_cfg(cfg)
	scale := if ctx.ft.scale == 0 { f32(1) } else { ctx.ft.scale }
	ctx.ft.fons.draw_text(x * scale, y * scale, text_) // TODO: check offsets/alignment
}

// draw_text draws the string in `text_` starting at top-left position `x`,`y` using
// default text settings.
pub fn (ctx &Context) draw_text_def(x int, y int, text string) {
	ctx.draw_text(x, y, text)
}

// flush prepares the font for use.
pub fn (ft &FT) flush() {
	sfons.flush(ft.fons)
}

// text_width returns the width of the `string` `s` in pixels.
pub fn (ctx &Context) text_width(s string) int {
	$if macos {
		if ctx.native_rendering {
			return C.darwin_text_width(s)
		}
	}
	// ctx.set_text_cfg(cfg) TODO
	if !ctx.font_inited {
		return 0
	}
	mut buf := [4]f32{}
	ctx.ft.fons.text_bounds(0, 0, s, &buf[0])
	if s.ends_with(' ') {
		return int((buf[2] - buf[0]) / ctx.scale) +
			ctx.text_width('i') // TODO fix this in fontstash?
	}
	res := int((buf[2] - buf[0]) / ctx.scale)
	// println('TW "$s" = $res')
	$if macos {
		if ctx.native_rendering {
			return res * 2
		}
	}
	return int((buf[2] - buf[0]) / ctx.scale)
}

// text_height returns the height of the `string` `s` in pixels.
pub fn (ctx &Context) text_height(s string) int {
	// ctx.set_text_cfg(cfg) TODO
	if !ctx.font_inited {
		return 0
	}
	mut buf := [4]f32{}
	ctx.ft.fons.text_bounds(0, 0, s, &buf[0])
	return int((buf[3] - buf[1]) / ctx.scale)
}

// text_size returns the width and height of the `string` `s` in pixels.
pub fn (ctx &Context) text_size(s string) (int, int) {
	// ctx.set_text_cfg(cfg) TODO
	if !ctx.font_inited {
		return 0, 0
	}
	mut buf := [4]f32{}
	ctx.ft.fons.text_bounds(0, 0, s, &buf[0])
	return int((buf[2] - buf[0]) / ctx.scale), int((buf[3] - buf[1]) / ctx.scale)
}
