// Copyright (c) 2019-2020 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 builtin


//pub fn vsyscall(id int
//

/*
pub const (
	sys_write = 1
	sys_mkdir = 83
)
const (
	stdin_value = 0
	stdout_value = 1
	stderr_value  = 2
)

fn C.puts(charptr)
*/

pub fn println(s string) {
	//  TODO: a syscall sys_write on linux works, except for the v repl.
	//  Probably it is a stdio buffering issue. Needs more testing...
	//	$if linux {
	//		$if !android {
	//			snl := s + '\n'
	//			C.syscall(/* sys_write */ 1, /* stdout_value */ 1, snl.str, s.len+1)
	//			return
	//		}
	//	}
	C.printf('%.*s\n', s.len, s.str)
}

fn print_backtrace_skipping_top_frames_msvc(skipframes int) bool {
	println('not implemented, see builtin_windows.v')
	return false
}

fn print_backtrace_skipping_top_frames_mingw(skipframes int) bool {
	println('not implemented, see builtin_windows.v')
	return false
}

fn print_backtrace_skipping_top_frames_nix(xskipframes int) bool {
	skipframes := xskipframes + 2
	$if macos {
		return print_backtrace_skipping_top_frames_mac(skipframes)
	}
	$if linux {
		return print_backtrace_skipping_top_frames_linux(skipframes)
	}
	$if freebsd {
		return print_backtrace_skipping_top_frames_freebsd(skipframes)
	}
	return false
}

// the functions below are not called outside this file,
// so there is no need to have their twins in builtin_windows.v
fn print_backtrace_skipping_top_frames_mac(skipframes int) bool {
	$if macos {
		buffer := [100]byteptr
		nr_ptrs := C.backtrace(buffer, 100)
		backtrace_symbols_fd(&buffer[skipframes], nr_ptrs - skipframes, 1)
	}
	return true
}

fn print_backtrace_skipping_top_frames_freebsd(skipframes int) bool {
	$if freebsd {
		buffer := [100]byteptr
		nr_ptrs := C.backtrace(buffer, 100)
		C.backtrace_symbols_fd(&buffer[skipframes], nr_ptrs - skipframes, 1)
	}
	return true
}

fn print_backtrace_skipping_top_frames_linux(skipframes int) bool {
	$if tinyc {
		println('TODO: print_backtrace_skipping_top_frames_linux $skipframes with tcc fails tests with "stack smashing detected" .')
		return false
	}
	$if !android {
		// backtrace is not available on Android.
		$if glibc {
			buffer := [100]byteptr
			nr_ptrs := C.backtrace(buffer, 100)
			nr_actual_frames := nr_ptrs - skipframes
			mut sframes := []string
			//////csymbols := C.backtrace_symbols(*voidptr(&buffer[skipframes]), nr_actual_frames)
			csymbols := C.backtrace_symbols(&buffer[skipframes], nr_actual_frames)
			for i in 0 .. nr_actual_frames {
				sframes << tos2(csymbols[i])
			}
			for sframe in sframes {
				executable := sframe.all_before('(')
				addr := sframe.all_after('[').all_before(']')
				beforeaddr := sframe.all_before('[')
				cmd := 'addr2line -e $executable $addr'
				// taken from os, to avoid depending on the os module inside builtin.v
				f := C.popen(cmd.str, 'r')
				if isnil(f) {
					println(sframe)
					continue
				}
				buf := [1000]byte
				mut output := ''
				for C.fgets(buf, 1000, f) != 0 {
					output += tos(buf, vstrlen(buf))
				}
				output = output.trim_space() + ':'
				if C.pclose(f) != 0 {
					println(sframe)
					continue
				}
				if output in ['??:0:', '??:?:'] {
					output = ''
				}
				//println('${output:-46s} | ${addr:14s} | $beforeaddr') // QTODO
			}
			// C.backtrace_symbols_fd(*voidptr(&buffer[skipframes]), nr_actual_frames, 1)
			return true
		} $else {
			println('backtrace_symbols_fd is missing, so printing backtraces is not available.\n')
			println('Some libc implementations like musl simply do not provide it.')
		}
	}
	return false
}