// 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)
*/

fn builtin_init() {
	// Do nothing
}

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(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)
	}
	$if netbsd {
		return print_backtrace_skipping_top_frames_freebsd(skipframes)
	}
	$if openbsd {
		return print_backtrace_skipping_top_frames_freebsd(skipframes)
	}
	println('print_backtrace_skipping_top_frames is not implemented. skipframes: $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)
		C.backtrace_symbols_fd(&buffer[skipframes], nr_ptrs - skipframes, 2)
	}
	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, 2)
	}
	return true
}

fn print_backtrace_skipping_top_frames_linux(skipframes int) bool {
	$if android {
		eprintln('On Android no backtrace is available.')
		return false
	}
	$if !glibc {
		eprintln('backtrace_symbols is missing => printing backtraces is not available.')
		eprintln('Some libc implementations like musl simply do not provide it.')
		return false
	}
	$if tinyc {
		eprintln('TODO: print_backtrace_skipping_top_frames_linux $skipframes')
		eprintln('with tcc fails tests with "stack smashing detected" .')
		return false
	}
	buffer := [100]byteptr
	nr_ptrs := C.backtrace(buffer, 100)
	nr_actual_frames := nr_ptrs - skipframes
	mut sframes := []string{}
	//////csymbols := 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( byteptr(csymbols[i]) )
	}
	for sframe in sframes {
		executable := sframe.all_before('(')
		addr := sframe.all_after('[').all_before(']')
		beforeaddr := sframe.all_before('[')
		cmd := 'addr2line -e $executable $addr'
		// taken from os, to avoid depending on the os module inside builtin.v
		f := C.popen(cmd.str, 'r')
		if isnil(f) {
			eprintln(sframe)
			continue
		}
		buf := [1000]byte
		mut output := ''
		for C.fgets(charptr(buf), 1000, f) != 0 {
			output += tos(buf, vstrlen(buf))
		}
		output = output.trim_space() + ':'
		if C.pclose(f) != 0 {
			eprintln(sframe)
			continue
		}
		if output in ['??:0:', '??:?:'] {
			output = ''
		}
		// See http://wiki.dwarfstd.org/index.php?title=Path_Discriminators
		// NB: it is shortened here to just d. , just so that it fits, and so
		// that the common error file:lineno: line format is enforced.
		output = output.replace(' (discriminator', ': (d.')
		eprintln('${output:-46s} | ${addr:14s} | $beforeaddr')
	}
	return true
}