enum ErrorValueKind : u32 {
	ErrorValue_Error,
	ErrorValue_Warning,
};

struct ErrorValue {
	ErrorValueKind kind;
	TokenPos       pos;
	TokenPos       end;
	Array<String>  msgs;
};

struct ErrorCollector {
	TokenPos prev;
	std::atomic<i64>  count;
	std::atomic<i64>  warning_count;
	std::atomic<bool> in_block;

	RecursiveMutex    mutex;
	BlockingMutex     path_mutex;

	Array<ErrorValue> error_values;
	ErrorValue        curr_error_value;
	std::atomic<bool> curr_error_value_set;
};

gb_global ErrorCollector global_error_collector;


gb_internal void push_error_value(TokenPos const &pos, ErrorValueKind kind = ErrorValue_Error) {
	GB_ASSERT_MSG(global_error_collector.curr_error_value_set.load() == false, "Possible race condition in error handling system, please report this with an issue");
	ErrorValue ev = {kind, pos};
	ev.msgs.allocator = heap_allocator();

	global_error_collector.curr_error_value = ev;
	global_error_collector.curr_error_value_set.store(true);
}

gb_internal void pop_error_value(void) {
	if (global_error_collector.curr_error_value_set.load()) {
		array_add(&global_error_collector.error_values, global_error_collector.curr_error_value);

		global_error_collector.curr_error_value = {};
		global_error_collector.curr_error_value_set.store(false);
	}
}


gb_internal void try_pop_error_value(void) {
	if (!global_error_collector.in_block.load()) {
		pop_error_value();
	}
}

gb_internal ErrorValue *get_error_value(void) {
	GB_ASSERT_MSG(global_error_collector.curr_error_value_set.load() == true, "Possible race condition in error handling system, please report this with an issue");
	return &global_error_collector.curr_error_value;
}



gb_internal bool any_errors(void) {
	return global_error_collector.count.load() != 0;
}



gb_internal void init_global_error_collector(void) {
	array_init(&global_error_collector.error_values, heap_allocator());
	array_init(&global_file_path_strings, heap_allocator(), 1, 4096);
	array_init(&global_files,             heap_allocator(), 1, 4096);
}

gb_internal isize MAX_ERROR_COLLECTOR_COUNT(void);


// temporary
// defined in build_settings.cpp
gb_internal char *token_pos_to_string(TokenPos const &pos);

gb_internal bool set_file_path_string(i32 index, String const &path) {
	bool ok = false;
	GB_ASSERT(index >= 0);
	mutex_lock(&global_error_collector.path_mutex);

	if (index >= global_file_path_strings.count) {
		array_resize(&global_file_path_strings, index+1);
	}
	String prev = global_file_path_strings[index];
	if (prev.len == 0) {
		global_file_path_strings[index] = path;
		ok = true;
	}

	mutex_unlock(&global_error_collector.path_mutex);
	return ok;
}

gb_internal bool thread_safe_set_ast_file_from_id(i32 index, AstFile *file) {
	bool ok = false;
	GB_ASSERT(index >= 0);
	mutex_lock(&global_error_collector.path_mutex);

	if (index >= global_files.count) {
		array_resize(&global_files, index+1);
	}
	AstFile *prev = global_files[index];
	if (prev == nullptr) {
		global_files[index] = file;
		ok = true;
	}

	mutex_unlock(&global_error_collector.path_mutex);
	return ok;
}

gb_internal String get_file_path_string(i32 index) {
	GB_ASSERT(index >= 0);
	mutex_lock(&global_error_collector.path_mutex);

	String path = {};
	if (index < global_file_path_strings.count) {
		path = global_file_path_strings[index];
	}

	mutex_unlock(&global_error_collector.path_mutex);
	return path;
}

gb_internal AstFile *thread_safe_get_ast_file_from_id(i32 index) {
	GB_ASSERT(index >= 0);
	mutex_lock(&global_error_collector.path_mutex);

	AstFile *file = nullptr;
	if (index < global_files.count) {
		file = global_files[index];
	}

	mutex_unlock(&global_error_collector.path_mutex);
	return file;
}



// NOTE: defined in build_settings.cpp
gb_internal bool global_warnings_as_errors(void);
gb_internal bool global_ignore_warnings(void);
gb_internal bool show_error_line(void);
gb_internal bool terse_errors(void);
gb_internal bool json_errors(void);
gb_internal bool has_ansi_terminal_colours(void);
gb_internal gbString get_file_line_as_string(TokenPos const &pos, i32 *offset);

gb_internal void warning(Token const &token, char const *fmt, ...);
gb_internal void error(Token const &token, char const *fmt, ...);
gb_internal void error(TokenPos pos, char const *fmt, ...);
gb_internal void error_line(char const *fmt, ...);
gb_internal void syntax_error(Token const &token, char const *fmt, ...);
gb_internal void syntax_error(TokenPos pos, char const *fmt, ...);
gb_internal void syntax_warning(Token const &token, char const *fmt, ...);
gb_internal void compiler_error(char const *fmt, ...);
gb_internal void print_all_errors(void);


#define ERROR_OUT_PROC(name) void name(char const *fmt, va_list va)
typedef ERROR_OUT_PROC(ErrorOutProc);

gb_internal ERROR_OUT_PROC(default_error_out_va) {
	char buf[4096] = {};
	isize len = gb_snprintf_va(buf, gb_size_of(buf), fmt, va);
	isize n = len-1;

	if (n > 0) {
		String msg = copy_string(permanent_allocator(), {(u8 *)buf, n});
		ErrorValue *ev = get_error_value();
		array_add(&ev->msgs, msg);
	}
}

gb_global ErrorOutProc *error_out_va = default_error_out_va;

gb_internal void begin_error_block(void) {
	mutex_lock(&global_error_collector.mutex);
	global_error_collector.in_block.store(true);
}

gb_internal void end_error_block(void) {
	pop_error_value();
	global_error_collector.in_block.store(false);
	mutex_unlock(&global_error_collector.mutex);
}

#define ERROR_BLOCK() begin_error_block(); defer (end_error_block())



gb_internal void error_out(char const *fmt, ...) {
	va_list va;
	va_start(va, fmt);
	error_out_va(fmt, va);
	va_end(va);
}

enum TerminalStyle {
	TerminalStyle_Normal,
	TerminalStyle_Bold,
	TerminalStyle_Underline,
};

enum TerminalColour {
	TerminalColour_White,
	TerminalColour_Red,
	TerminalColour_Yellow,
	TerminalColour_Green,
	TerminalColour_Cyan,
	TerminalColour_Blue,
	TerminalColour_Purple,
	TerminalColour_Black,
};

gb_internal void terminal_set_colours(TerminalStyle style, TerminalColour foreground) {
	if (has_ansi_terminal_colours()) {
		char const *ss = "0";
		switch (style) {
		case TerminalStyle_Normal:    ss = "0"; break;
		case TerminalStyle_Bold:      ss = "1"; break;
		case TerminalStyle_Underline: ss = "4"; break;
		}
		switch (foreground) {
		case TerminalColour_White:  error_out("\x1b[%s;37m", ss); break;
		case TerminalColour_Red:    error_out("\x1b[%s;31m", ss); break;
		case TerminalColour_Yellow: error_out("\x1b[%s;33m", ss); break;
		case TerminalColour_Green:  error_out("\x1b[%s;32m", ss); break;
		case TerminalColour_Cyan:   error_out("\x1b[%s;36m", ss); break;
		case TerminalColour_Blue:   error_out("\x1b[%s;34m", ss); break;
		case TerminalColour_Purple: error_out("\x1b[%s;35m", ss); break;
		case TerminalColour_Black:  error_out("\x1b[%s;30m", ss); break;
		}
	}
}
gb_internal void terminal_reset_colours(void) {
	if (has_ansi_terminal_colours()) {
		error_out("\x1b[0m");
	}
}


gb_internal bool show_error_on_line(TokenPos const &pos, TokenPos end) {
	get_error_value()->end = end;
	if (!show_error_line()) {
		return false;
	}

	i32 offset = 0;
	gbString the_line = get_file_line_as_string(pos, &offset);
	defer (gb_string_free(the_line));

	if (the_line != nullptr) {
		char const *line_text = the_line;
		isize line_len = gb_string_length(the_line);

		// TODO(bill): This assumes ASCII

		enum {
			MAX_LINE_LENGTH  = 80,
			MAX_TAB_WIDTH    = 8,
			ELLIPSIS_PADDING = 8, // `...  ...`
			MAX_LINE_LENGTH_PADDED = MAX_LINE_LENGTH-MAX_TAB_WIDTH-ELLIPSIS_PADDING,
		};

		error_out("\t");

		terminal_set_colours(TerminalStyle_Bold, TerminalColour_White);


		i32 error_length = gb_max(end.offset - pos.offset, 1);

		isize squiggle_extra = 0;

		if (line_len > MAX_LINE_LENGTH_PADDED) {
			i32 left = MAX_TAB_WIDTH;
			if (offset > 0) {
				line_text += offset-left;
				line_len  -= offset-left;
				offset = left+MAX_TAB_WIDTH/2;
			}
			if (line_len > MAX_LINE_LENGTH_PADDED) {
				line_len = MAX_LINE_LENGTH_PADDED;
				if (error_length > line_len-left) {
					error_length = cast(i32)line_len - left;
					squiggle_extra = 1;
				}
			}
			if (offset > 0) {
				error_out("... %.*s ...", cast(i32)line_len, line_text);
			} else {
				error_out("%.*s ...", cast(i32)line_len, line_text);
			}
		} else {
			error_out("%.*s", cast(i32)line_len, line_text);
		}
		error_out("\n\t");

		for (i32 i = 0; i < offset; i++) {
			error_out(" ");
		}

		terminal_set_colours(TerminalStyle_Bold, TerminalColour_Green);

		error_out("^");
		if (end.file_id == pos.file_id) {
			if (end.line > pos.line) {
				for (i32 i = offset; i < line_len; i++) {
					error_out("~");
				}
			} else if (end.line == pos.line && end.column > pos.column) {
				for (i32 i = 1; i < error_length-1+squiggle_extra; i++) {
					error_out("~");
				}
				if (error_length > 1 && squiggle_extra == 0) {
					error_out("^");
				}
			}
		}

		terminal_reset_colours();

		error_out("\n");
		return true;
	}
	return false;
}

gb_internal void error_out_empty(void) {
	error_out("");
}
gb_internal void error_out_pos(TokenPos pos) {
	terminal_set_colours(TerminalStyle_Bold, TerminalColour_White);
	error_out("%s ", token_pos_to_string(pos));
	terminal_reset_colours();
}

gb_internal void error_out_coloured(char const *str, TerminalStyle style, TerminalColour foreground) {
	terminal_set_colours(style, foreground);
	error_out(str);
	terminal_reset_colours();
}



gb_internal void error_va(TokenPos const &pos, TokenPos end, char const *fmt, va_list va) {
	global_error_collector.count.fetch_add(1);
	if (global_error_collector.count > MAX_ERROR_COLLECTOR_COUNT()) {
		print_all_errors();
		gb_exit(1);
	}
	mutex_lock(&global_error_collector.mutex);

	push_error_value(pos, ErrorValue_Error);
	// NOTE(bill): Duplicate error, skip it
	if (pos.line == 0) {
		error_out_empty();
		error_out_coloured("Error: ", TerminalStyle_Normal, TerminalColour_Red);
		error_out_va(fmt, va);
		error_out("\n");
	} else if (global_error_collector.prev != pos) {
		global_error_collector.prev = pos;
		error_out_pos(pos);
		if (has_ansi_terminal_colours()) {
			error_out_coloured("Error: ", TerminalStyle_Normal, TerminalColour_Red);
		}
		error_out_va(fmt, va);
		error_out("\n");
		show_error_on_line(pos, end);
	} else {
		global_error_collector.count.fetch_sub(1);
	}
	try_pop_error_value();
	mutex_unlock(&global_error_collector.mutex);
}

gb_internal void warning_va(TokenPos const &pos, TokenPos end, char const *fmt, va_list va) {
	if (global_warnings_as_errors()) {
		error_va(pos, end, fmt, va);
		return;
	}
	global_error_collector.warning_count.fetch_add(1);
	mutex_lock(&global_error_collector.mutex);

	push_error_value(pos, ErrorValue_Warning);

	if (!global_ignore_warnings()) {
		// NOTE(bill): Duplicate error, skip it
		if (pos.line == 0) {
			error_out_empty();
			error_out_coloured("Warning: ", TerminalStyle_Normal, TerminalColour_Yellow);
			error_out_va(fmt, va);
			error_out("\n");
		} else if (global_error_collector.prev != pos) {
			global_error_collector.prev = pos;
			error_out_pos(pos);
			error_out_coloured("Warning: ", TerminalStyle_Normal, TerminalColour_Yellow);
			error_out_va(fmt, va);
			error_out("\n");
			show_error_on_line(pos, end);
		}
	}
	try_pop_error_value();
	mutex_unlock(&global_error_collector.mutex);
}


gb_internal void error_line_va(char const *fmt, va_list va) {
	error_out_va(fmt, va);
}

gb_internal void error_no_newline_va(TokenPos const &pos, char const *fmt, va_list va) {
	global_error_collector.count.fetch_add(1);
	if (global_error_collector.count.load() > MAX_ERROR_COLLECTOR_COUNT()) {
		print_all_errors();
		gb_exit(1);
	}
	mutex_lock(&global_error_collector.mutex);

	push_error_value(pos, ErrorValue_Error);

	// NOTE(bill): Duplicate error, skip it
	if (pos.line == 0) {
		error_out_empty();
		error_out_coloured("Error: ", TerminalStyle_Normal, TerminalColour_Red);
		error_out_va(fmt, va);
	} else if (global_error_collector.prev != pos) {
		global_error_collector.prev = pos;
		error_out_pos(pos);
		if (has_ansi_terminal_colours()) {
			error_out_coloured("Error: ", TerminalStyle_Normal, TerminalColour_Red);
		}
		error_out_va(fmt, va);
	}

	try_pop_error_value();
	mutex_unlock(&global_error_collector.mutex);
}


gb_internal void syntax_error_va(TokenPos const &pos, TokenPos end, char const *fmt, va_list va) {
	global_error_collector.count.fetch_add(1);
	if (global_error_collector.count > MAX_ERROR_COLLECTOR_COUNT()) {
		print_all_errors();
		gb_exit(1);
	}
	mutex_lock(&global_error_collector.mutex);

	push_error_value(pos, ErrorValue_Warning);

	// NOTE(bill): Duplicate error, skip it
	if (global_error_collector.prev != pos) {
		global_error_collector.prev = pos;
		error_out_pos(pos);
		error_out_coloured("Syntax Error: ", TerminalStyle_Normal, TerminalColour_Red);
		error_out_va(fmt, va);
		error_out("\n");
		show_error_on_line(pos, end);
	} else if (pos.line == 0) {
		error_out_empty();
		error_out_coloured("Syntax Error: ", TerminalStyle_Normal, TerminalColour_Red);
		error_out_va(fmt, va);
		error_out("\n");
	}

	try_pop_error_value();
	mutex_unlock(&global_error_collector.mutex);
}

gb_internal void syntax_error_with_verbose_va(TokenPos const &pos, TokenPos end, char const *fmt, va_list va) {
	global_error_collector.count.fetch_add(1);
	if (global_error_collector.count > MAX_ERROR_COLLECTOR_COUNT()) {
		print_all_errors();
		gb_exit(1);
	}
	mutex_lock(&global_error_collector.mutex);

	push_error_value(pos, ErrorValue_Warning);

	// NOTE(bill): Duplicate error, skip it
	if (pos.line == 0) {
		error_out_empty();
		error_out_coloured("Syntax_Error: ", TerminalStyle_Normal, TerminalColour_Red);
		error_out_va(fmt, va);
		error_out("\n");
	} else if (global_error_collector.prev != pos) {
		global_error_collector.prev = pos;
		error_out_pos(pos);
		if (has_ansi_terminal_colours()) {
			error_out_coloured("Syntax_Error: ", TerminalStyle_Normal, TerminalColour_Red);
		}
		error_out_va(fmt, va);
		error_out("\n");
		show_error_on_line(pos, end);
	}

	try_pop_error_value();
	mutex_unlock(&global_error_collector.mutex);
}


gb_internal void syntax_warning_va(TokenPos const &pos, TokenPos end, char const *fmt, va_list va) {
	if (global_warnings_as_errors()) {
		syntax_error_va(pos, end, fmt, va);
		return;
	}
	mutex_lock(&global_error_collector.mutex);
	global_error_collector.warning_count++;


	push_error_value(pos, ErrorValue_Warning);

	if (!global_ignore_warnings()) {
		// NOTE(bill): Duplicate error, skip it
		if (global_error_collector.prev != pos) {
			global_error_collector.prev = pos;
			error_out_pos(pos);
			error_out_coloured("Syntax Warning: ", TerminalStyle_Normal, TerminalColour_Yellow);
			error_out_va(fmt, va);
			error_out("\n");
			// show_error_on_line(pos, end);
		} else if (pos.line == 0) {
			error_out_empty();
			error_out_coloured("Syntax Warning: ", TerminalStyle_Normal, TerminalColour_Yellow);
			error_out_va(fmt, va);
			error_out("\n");
		}
	}

	try_pop_error_value();
	mutex_unlock(&global_error_collector.mutex);
}



gb_internal void warning(Token const &token, char const *fmt, ...) {
	va_list va;
	va_start(va, fmt);
	warning_va(token.pos, {}, fmt, va);
	va_end(va);
}

gb_internal void error(Token const &token, char const *fmt, ...) {
	va_list va;
	va_start(va, fmt);
	error_va(token.pos, {}, fmt, va);
	va_end(va);
}

gb_internal void error(TokenPos pos, char const *fmt, ...) {
	va_list va;
	va_start(va, fmt);
	Token token = {};
	token.pos = pos;
	error_va(pos, {}, fmt, va);
	va_end(va);
}

gb_internal void error_line(char const *fmt, ...) {
	va_list va;
	va_start(va, fmt);
	error_line_va(fmt, va);
	va_end(va);
}


gb_internal void syntax_error(Token const &token, char const *fmt, ...) {
	va_list va;
	va_start(va, fmt);
	syntax_error_va(token.pos, {}, fmt, va);
	va_end(va);
}

gb_internal void syntax_error(TokenPos pos, char const *fmt, ...) {
	va_list va;
	va_start(va, fmt);
	syntax_error_va(pos, {}, fmt, va);
	va_end(va);
}

gb_internal void syntax_warning(Token const &token, char const *fmt, ...) {
	va_list va;
	va_start(va, fmt);
	syntax_warning_va(token.pos, {}, fmt, va);
	va_end(va);
}

gb_internal void syntax_error_with_verbose(TokenPos pos, TokenPos end, char const *fmt, ...) {
	va_list va;
	va_start(va, fmt);
	syntax_error_with_verbose_va(pos, end, fmt, va);
	va_end(va);
}



gb_internal void compiler_error(char const *fmt, ...) {
	if (any_errors()) {
		print_all_errors();
	}

	va_list va;

	va_start(va, fmt);
	gb_printf_err("Internal Compiler Error: %s\n",
	              gb_bprintf_va(fmt, va));
	va_end(va);
	GB_DEBUG_TRAP();
	gb_exit(1);
}


gb_internal void exit_with_errors(void) {
	if (any_errors()) {
		print_all_errors();
	}
	gb_exit(1);
}



gb_internal int error_value_cmp(void const *a, void const *b) {
	ErrorValue *x = cast(ErrorValue *)a;
	ErrorValue *y = cast(ErrorValue *)b;
	return token_pos_cmp(x->pos, y->pos);
}

gb_internal void print_all_errors(void) {
	auto const &escape_char = [](gbFile *f, u8 c) {
		switch (c) {
		case '\n': gb_file_write(f, "\\n",  2); break;
		case '"':  gb_file_write(f, "\\\"", 2); break;
		case '\\': gb_file_write(f, "\\\\", 2); break;
		case '\b': gb_file_write(f, "\\b",  2); break;
		case '\f': gb_file_write(f, "\\f",  2); break;
		case '\r': gb_file_write(f, "\\r",  2); break;
		case '\t': gb_file_write(f, "\\t",  2); break;
		default:
			if ('\x00' <= c && c <= '\x1f') {
				gb_fprintf(f, "\\u%04x", c);
			} else {
				gb_file_write(f, &c, 1);
			}
			break;
		}
	};

	GB_ASSERT(any_errors());
	gbFile *f = gb_file_get_standard(gbFileStandard_Error);

	array_sort(global_error_collector.error_values, error_value_cmp);


	if (json_errors()) {
		gb_fprintf(f, "{\n");
		gb_fprintf(f, "\t\"error_count\": %td,\n", global_error_collector.error_values.count);
		gb_fprintf(f, "\t\"errors\": [\n");
		for_array(i, global_error_collector.error_values) {
			ErrorValue ev = global_error_collector.error_values[i];

			gb_fprintf(f, "\t\t{\n");

			gb_fprintf(f, "\t\t\t\"pos\": {\n");

			if (ev.pos.file_id) {
				gb_fprintf(f, "\t\t\t\t\"file\": \"");
				String file = get_file_path_string(ev.pos.file_id);
				for (isize k = 0; k < file.len; k++) {
					escape_char(f, file.text[k]);
				}
				gb_fprintf(f, "\",\n");
				gb_fprintf(f, "\t\t\t\t\"offset\": %d,\n", ev.pos.offset);
				gb_fprintf(f, "\t\t\t\t\"line\": %d,\n", ev.pos.line);
				gb_fprintf(f, "\t\t\t\t\"column\": %d,\n", ev.pos.column);
				i32 end_column = gb_max(ev.end.column, ev.pos.column);
				gb_fprintf(f, "\t\t\t\t\"end_column\": %d\n", end_column);
				gb_fprintf(f, "\t\t\t},\n");
			}

			gb_fprintf(f, "\t\t\t\"msgs\": [\n");

			if (ev.msgs.count > 1) {
				gb_fprintf(f, "\t\t\t\t\"");

				for (isize j = 1; j < ev.msgs.count; j++) {
					String msg = ev.msgs[j];
					for (isize k = 0; k < msg.len; k++) {
						u8 c = msg.text[k];
						if (c == '\n') {
							if (k+1 == msg.len && j+1 == ev.msgs.count) {
								// don't do the last one
							} else {
								gb_fprintf(f, "\",\n");
								gb_fprintf(f, "\t\t\t\t\"");
							}
						} else {
							escape_char(f, c);
						}
					}
				}
				gb_fprintf(f, "\"\n");
			}
			gb_fprintf(f, "\t\t\t]\n");
			gb_fprintf(f, "\t\t}");
			if (i+1 != global_error_collector.error_values.count) {
				gb_fprintf(f, ",");
			}
			gb_fprintf(f, "\n");
		}

		gb_fprintf(f, "\t]\n");
		gb_fprintf(f, "}\n");
	} else {
		for_array(i, global_error_collector.error_values) {
			ErrorValue ev = global_error_collector.error_values[i];
			for (isize j = 0; j < ev.msgs.count; j++) {
				String msg = ev.msgs[j];
				gb_file_write(f, msg.text, msg.len);

				if (terse_errors() && string_contains_char(msg, '\n')) {
					break;
				}
			}
		}
	}
}