package main

import "core:fmt"
import "core:log"
import "core:math"
import "core:mem"
import "core:os"
import "core:slice"
import "core:strconv"
import "core:strings"
import "core:unicode/utf8"

import sdl "vendor:sdl2"
import ttf "vendor:sdl2/ttf"

// Application constants
WINDOW_WIDTH :: 1200
WINDOW_HEIGHT :: 800
TAB_HEIGHT :: 30
LINE_NUMBER_WIDTH :: 60
FONT_SIZE :: 14
TEXT_PADDING :: 10

app: App

main :: proc() {
	context.logger = log.create_console_logger(.Debug)
	defer log.destroy_console_logger(context.logger)

	// Get command line arguments
	args := os.args[1:]

	ok := false
	app.config, ok = parse_config("config.ini")
	if !ok {
		log.fatal("failed to parse config file")
		return
	}
	defer config_destroy(app.config)

	log.debug("app config:")
	log.debug(app.config)

	if init_sdl() != 0 {
		log.fatal("failed to initialize sdl")
		return
	}
	defer cleanup_sdl()

	sdl.SetWindowMinimumSize(app.window, 300, 400)

	// Create tabs from command line arguments
	if len(args) == 0 {
		// Create empty tab if no files specified
		create_tab("Untitled", "")
	} else {
		for filename in args {
			content := ""
			if data, ok := os.read_entire_file(filename); ok {
				content = string(data)
			} else {
				fmt.printf("Warning: Could not read file '%s'\n", filename)
				content = fmt.tprintf("Error: Could not read file '%s'", filename)
			}

			// Extract filename for tab
			tab_name := filename
			if idx := strings.last_index(filename, "/"); idx != -1 {
				tab_name = filename[idx+1:]
			}
			if idx := strings.last_index(tab_name, "\\"); idx != -1 {
				tab_name = tab_name[idx+1:]
			}

			create_tab(tab_name, content)
		}
	}

	app.active_tab = 0
	calculate_layout()

	// Main loop
	app.running = true
	for app.running {
		handle_events()
		render()
		sdl.Delay(16) // ~60 FPS
	}
}

init_sdl :: proc() -> int {
	if sdl.Init(sdl.INIT_VIDEO) < 0 {
		fmt.printf("SDL could not initialize: %s\n", sdl.GetError())
		return -1
	}

	if ttf.Init() < 0 {
		fmt.printf("TTF could not initialize: %s\n", ttf.GetError())
		return -1
	}

	app.window = sdl.CreateWindow(
		"notepad",
		sdl.WINDOWPOS_CENTERED, sdl.WINDOWPOS_CENTERED,
		WINDOW_WIDTH, WINDOW_HEIGHT,
		sdl.WINDOW_SHOWN | sdl.WINDOW_RESIZABLE
	)

	if app.window == nil {
		fmt.printf("Window could not be created: %s\n", sdl.GetError())
		return -1
	}

	app.renderer = sdl.CreateRenderer(app.window, -1, sdl.RENDERER_ACCELERATED)
	if app.renderer == nil {
		fmt.printf("Renderer could not be created: %s\n", sdl.GetError())
		return -1
	}

	font_cstring := strings.clone_to_cstring(app.config.font)
	defer delete(font_cstring)
	app.font = ttf.OpenFont(font_cstring, i32(app.config.font_size))

	if app.font == nil {
		log.fatal("Could not load font")
		return -1
	}

	// Calculate character dimensions
	w, h: i32
	if ttf.SizeText(app.font, "W", &w, &h) == 0 {
		app.char_width = w
		app.char_height = h
	} else {
		app.char_width = 8
		app.char_height = 16
	}

	return 0
}

cleanup_sdl :: proc() {
	if app.font != nil do ttf.CloseFont(app.font)
	if app.renderer != nil do sdl.DestroyRenderer(app.renderer)
	if app.window != nil do sdl.DestroyWindow(app.window)

	for &tab in app.tabs {
		delete(tab.buffer.lines)
	}
	delete(app.tabs)

	ttf.Quit()
	sdl.Quit()
}

create_tab :: proc(name: string, content: string) {
	tab := Tab{
		name = strings.clone(name),
		buffer = Text_Buffer{},
	}

	tab.buffer.filename = strings.clone(name)
	tab.buffer.lines = make([dynamic]string)

	// Split content into lines
	if len(content) > 0 {
		lines := strings.split(content, "\n")
		defer delete(lines)
		for line in lines {
			append(&tab.buffer.lines, strings.clone(line))
		}
	} else {
		append(&tab.buffer.lines, "")
	}

	append(&app.tabs, tab)
}

calculate_layout :: proc() {
	w, h: i32
	sdl.GetWindowSize(app.window, &w, &h)

	app.text_area_width = w - LINE_NUMBER_WIDTH
	app.visible_lines = int((h - TAB_HEIGHT) / app.char_height) - 1

	// Calculate tab rectangles
	if len(app.tabs) > 0 {
		tab_width := w / i32(len(app.tabs))
		for i in 0..<len(app.tabs) {
			app.tabs[i].rect = {
				x = i32(i) * tab_width,
				y = 0,
				w = tab_width,
				h = TAB_HEIGHT,
			}
		}
	}
}

handle_events :: proc() {
	e: sdl.Event
	for sdl.PollEvent(&e) {
		#partial switch e.type {
		case sdl.EventType.QUIT:
			app.running = false

		case sdl.EventType.WINDOWEVENT:
			calculate_layout()

		case sdl.EventType.KEYDOWN:
			handle_key_down(e.key.keysym.scancode, e.key.keysym.mod)

		case sdl.EventType.TEXTINPUT:
			handle_text_input(string(cstring(&e.text.text[0])))

		case sdl.EventType.MOUSEBUTTONDOWN:
			handle_mouse_click(e.button.x, e.button.y)

		case sdl.EventType.MOUSEWHEEL:
			handle_scroll(e.wheel.y)
		}
	}

	// Handle cursor blinking
	current_time := sdl.GetTicks()
	if current_time - app.cursor_blink_timer > 500 {
		app.show_cursor = !app.show_cursor
		app.cursor_blink_timer = current_time
	}
}

handle_key_down :: proc(scancode: sdl.Scancode, modifiers: sdl.Keymod) {
	if len(app.tabs) == 0 do return

	buffer := &app.tabs[app.active_tab].buffer

	left_ctrl_pressed := (modifiers & sdl.KMOD_CTRL) == sdl.KMOD_LCTRL
	right_ctrl_pressed := (modifiers & sdl.KMOD_CTRL) == sdl.KMOD_RCTRL

	#partial switch scancode {
	case .S:
	if left_ctrl_pressed || right_ctrl_pressed {
		// TODO: Tidy up this code and optimize it for big files
		filename := buffer.filename

		builder := strings.builder_make()
		defer strings.builder_destroy(&builder)

		for line in buffer.lines {
			strings.write_string(&builder, line)
			strings.write_rune(&builder, '\n')
		}
		str := strings.to_string(builder)
		data := transmute([]u8)str

		ok := os.write_entire_file(filename, data)
	}
	case .TAB:
		// Switch tabs
		app.active_tab = (app.active_tab + 1) % len(app.tabs)

	case .RETURN:
		// Insert new line
		if buffer.cursor_line < len(buffer.lines) {
			current_line := buffer.lines[buffer.cursor_line]
			left_part := current_line[:buffer.cursor_col] if buffer.cursor_col <= len(current_line) else current_line
			right_part := current_line[buffer.cursor_col:] if buffer.cursor_col <= len(current_line) else ""

			buffer.lines[buffer.cursor_line] = strings.clone(left_part)
			inject_at(&buffer.lines, buffer.cursor_line + 1, strings.clone(right_part))

			buffer.cursor_line += 1
			buffer.cursor_col = 0
			buffer.modified = true
		}

	case .BACKSPACE:
		if buffer.cursor_col > 0 {
			// Remove character
			line := &buffer.lines[buffer.cursor_line]
			if buffer.cursor_col <= len(line^) {
				new_line := strings.concatenate({line^[:buffer.cursor_col-1], line^[buffer.cursor_col:]})
				delete(line^)
				line^ = new_line
				buffer.cursor_col -= 1
				buffer.modified = true
			}
		} else if buffer.cursor_line > 0 {
			// Join with previous line
			current_line := buffer.lines[buffer.cursor_line]
			prev_line := &buffer.lines[buffer.cursor_line - 1]
			buffer.cursor_col = len(prev_line^)

			new_line := strings.concatenate({prev_line^, current_line})
			delete(prev_line^)
			prev_line^ = new_line

			ordered_remove(&buffer.lines, buffer.cursor_line)
			buffer.cursor_line -= 1
			buffer.modified = true
		}

	case .DELETE:
		if buffer.cursor_line < len(buffer.lines) {
			line := &buffer.lines[buffer.cursor_line]
			if buffer.cursor_col < len(line^) {
				new_line := strings.concatenate({line^[:buffer.cursor_col], line^[buffer.cursor_col+1:]})
				delete(line^)
				line^ = new_line
				buffer.modified = true
			}
		}

	case .LEFT:
		if buffer.cursor_col > 0 {
			buffer.cursor_col -= 1
		} else if buffer.cursor_line > 0 {
			buffer.cursor_line -= 1
			buffer.cursor_col = len(buffer.lines[buffer.cursor_line])
		}

	case .RIGHT:
		if buffer.cursor_line < len(buffer.lines) {
			if buffer.cursor_col < len(buffer.lines[buffer.cursor_line]) {
				buffer.cursor_col += 1
			} else if buffer.cursor_line < len(buffer.lines) - 1 {
				buffer.cursor_line += 1
				buffer.cursor_col = 0
			}
		}

	case .UP:
		if buffer.cursor_line > 0 {
			buffer.cursor_line -= 1
			line_len := len(buffer.lines[buffer.cursor_line])
			if buffer.cursor_col > line_len {
				buffer.cursor_col = line_len
			}
		}

	case .DOWN:
		if buffer.cursor_line < len(buffer.lines) - 1 {
			buffer.cursor_line += 1
			line_len := len(buffer.lines[buffer.cursor_line])
			if buffer.cursor_col > line_len {
				buffer.cursor_col = line_len
			}
		}

	case .HOME:
		buffer.cursor_col = 0

	case .END:
		if buffer.cursor_line < len(buffer.lines) {
			buffer.cursor_col = len(buffer.lines[buffer.cursor_line])
		}

	case .PAGEUP:
		buffer.cursor_line = max(0, buffer.cursor_line - app.visible_lines)
		buffer.scroll_y = max(0, buffer.scroll_y - app.visible_lines)

	case .PAGEDOWN:
		buffer.cursor_line = min(len(buffer.lines) - 1, buffer.cursor_line + app.visible_lines)
		buffer.scroll_y = min(len(buffer.lines) - app.visible_lines, buffer.scroll_y + app.visible_lines)
	}

	// Reset cursor blink
	app.cursor_blink_timer = sdl.GetTicks()
	app.show_cursor = true
}

handle_text_input :: proc(text: string) {
	if len(app.tabs) == 0 do return

	buffer := &app.tabs[app.active_tab].buffer

	if buffer.cursor_line < len(buffer.lines) {
		line := &buffer.lines[buffer.cursor_line]
		if buffer.cursor_col <= len(line^) {
			new_line := strings.concatenate({
				line^[:buffer.cursor_col],
				text,
				line^[buffer.cursor_col:]
			})
			delete(line^)
			line^ = new_line
			buffer.cursor_col += len(text)
			buffer.modified = true
		}
	}

	// Reset cursor blink
	app.cursor_blink_timer = sdl.GetTicks()
	app.show_cursor = true
}

handle_mouse_click :: proc(x, y: i32) {
	// Check if click is on tabs
	if y <= TAB_HEIGHT {
		for i in 0..<len(app.tabs) {
			tab := &app.tabs[i]
			if x >= tab.rect.x && x < tab.rect.x + tab.rect.w {
				app.active_tab = i
				return
			}
		}
	}

	// Click in text area
	if len(app.tabs) > 0 && y > TAB_HEIGHT {
		buffer := &app.tabs[app.active_tab].buffer

		// Calculate line and column
		line := int((y - TAB_HEIGHT) / app.char_height) + buffer.scroll_y
		col := int((x - LINE_NUMBER_WIDTH) / app.char_width)

		if line >= 0 && line < len(buffer.lines) {
			buffer.cursor_line = line
			line_len := len(buffer.lines[line])
			buffer.cursor_col = min(col, line_len)
		}

		// Reset cursor blink
		app.cursor_blink_timer = sdl.GetTicks()
		app.show_cursor = true
	}
}

handle_scroll :: proc(y: i32) {
	if len(app.tabs) == 0 do return

	buffer := &app.tabs[app.active_tab].buffer
	buffer.scroll_y = max(0, min(len(buffer.lines) - app.visible_lines, buffer.scroll_y - int(y * 3)))
}

render :: proc() {
	sdl.SetRenderDrawColor(app.renderer, app.config.colours.background.r, app.config.colours.background.g, app.config.colours.background.b, app.config.colours.background.a)
	sdl.RenderClear(app.renderer)

	render_tabs()

	if len(app.tabs) > 0 {
		render_text_area()
	}

	sdl.RenderPresent(app.renderer)
}

render_tabs :: proc() {
	for i in 0..<len(app.tabs) {
		tab := &app.tabs[i]
		color := app.config.colours.inactive_tab if i != app.active_tab else app.config.colours.active_tab

		sdl.SetRenderDrawColor(app.renderer, color.r, color.g, color.b, color.a)
		sdl.RenderFillRect(app.renderer, &tab.rect)

		sdl.SetRenderDrawColor(app.renderer, app.config.colours.tab_border.r, app.config.colours.tab_border.g, app.config.colours.tab_border.b, app.config.colours.tab_border.a)
		sdl.RenderDrawRect(app.renderer, &tab.rect)

		// Render tab text
		render_text(tab.name, tab.rect.x + 10, tab.rect.y + 5, app.config.colours.text)
	}
}

render_text_area :: proc() {
	buffer := &app.tabs[app.active_tab].buffer

	// Render line number background
	line_bg_rect := sdl.Rect{0, TAB_HEIGHT, LINE_NUMBER_WIDTH, WINDOW_HEIGHT - TAB_HEIGHT}
	sdl.SetRenderDrawColor(
		app.renderer,
		app.config.colours.line_numbers_background.r,
		app.config.colours.line_numbers_background.g,
		app.config.colours.line_numbers_background.b,
		app.config.colours.line_numbers_background.a
	)
	sdl.RenderFillRect(app.renderer, &line_bg_rect)

	// Render separator line
	sdl.SetRenderDrawColor(
		app.renderer,
		app.config.colours.tab_border.r,
		app.config.colours.tab_border.g,
		app.config.colours.tab_border.b,
		app.config.colours.tab_border.a
	)
	sdl.RenderDrawLine(app.renderer, LINE_NUMBER_WIDTH, TAB_HEIGHT, LINE_NUMBER_WIDTH, WINDOW_HEIGHT)

	// Adjust scroll if cursor is outside visible area
	if buffer.cursor_line < buffer.scroll_y {
		buffer.scroll_y = buffer.cursor_line
	} else if buffer.cursor_line >= buffer.scroll_y + app.visible_lines {
		buffer.scroll_y = buffer.cursor_line - app.visible_lines + 1
	}

	// Render visible lines
	start_line := max(0, buffer.scroll_y)
	end_line := min(len(buffer.lines), start_line + app.visible_lines)

	for i in start_line..<end_line {
		y := TAB_HEIGHT + i32(i - start_line) * app.char_height

		// Render line number
		line_num_str := fmt.tprintf("%d", i + 1)
		render_text(line_num_str, 5, y, app.config.colours.line_numbers)

		// Render line text with wrapping
		if i < len(buffer.lines) {
			render_wrapped_line(buffer.lines[i], LINE_NUMBER_WIDTH + TEXT_PADDING, y, app.text_area_width - TEXT_PADDING * 2)
		}

		// Render cursor
		if i == buffer.cursor_line && app.show_cursor {
			cursor_x := LINE_NUMBER_WIDTH + TEXT_PADDING + i32(buffer.cursor_col) * app.char_width
			cursor_y := y

			sdl.SetRenderDrawColor(
				app.renderer,
				app.config.colours.cursor.r,
				app.config.colours.cursor.g,
				app.config.colours.cursor.b,
				app.config.colours.cursor.a
			)
			cursor_rect := sdl.Rect{cursor_x, cursor_y, 2, app.char_height}
			sdl.RenderFillRect(app.renderer, &cursor_rect)
		}
	}
}

render_text :: proc(text: string, x, y: i32, color: sdl.Color) {
	if app.font == nil || len(text) == 0 do return

	text_cstr := strings.clone_to_cstring(text)
	defer delete(text_cstr)

	surface := ttf.RenderText_Solid(app.font, text_cstr, color)
	if surface == nil do return
	defer sdl.FreeSurface(surface)

	texture := sdl.CreateTextureFromSurface(app.renderer, surface)
	if texture == nil do return
	defer sdl.DestroyTexture(texture)

	dst_rect := sdl.Rect{x, y, surface.w, surface.h}
	sdl.RenderCopy(app.renderer, texture, nil, &dst_rect)
}

render_wrapped_line :: proc(line: string, x, y: i32, max_width: i32) {
	if len(line) == 0 do return

	chars_per_line := int(max_width / app.char_width)
	if chars_per_line <= 0 do return

	// Simple word wrapping - break at word boundaries when possible
	words := strings.split(line, " ")
	defer delete(words)

	current_line := ""
	line_y := y

	for word in words {
		test_line := current_line
		if len(current_line) > 0 {
			test_line = strings.concatenate({current_line, " ", word})
		} else {
			test_line = word
		}

		if len(test_line) <= chars_per_line {
			current_line = test_line
		} else {
			// Render current line and start new one
			if len(current_line) > 0 {
				render_text(current_line, x, line_y, app.config.colours.text)
				line_y += app.char_height
			}
			current_line = word
		}
	}

	// Render final line
	if len(current_line) > 0 {
		render_text(current_line, x, line_y, app.config.colours.text)
	}
}