//! Displaying match data

#include <stdio.h>
#include <stdlib.h>
#include <string.h>

#include <macros.h>
#include <comp.h>
#include <display.h>

#define FLAGSET(f, flag) (( (f) & (flag) ) == (flag))
#define DFLAGSET(f, flagname) FLAGSET(f, DISPF_SHOW_ ## flagname)

// Returns number of bytes written to `dest`. Otherwise same as `strncpy()`.
static usize strncpy_n(char*pOUT dest, const char* restrict src, usize n)
{
	usize i;
	for(i=0;i<n;i++)
		if(! (*dest++ = *src++)) return i;
	dest[i] = 0;
	return i;
}

// Returns number of bytes written to (dest+strlen(dest)). Otherwise same as `strncat()`.
static inline usize strncat_n(char*pOUT dest, const char* restrict src, usize n)
{
	usize dl = strlen(dest);
	return strncpy_n(dest+dl, src, n);
}

//TODO: This works, but seems inherantly unsafe. Rewrite to use the above `strn*_n()` functions for better length tracking.
static usize _display_get_fmt(dispflags_t flags, bool matched, usize _len, char str[pOUT _len])
{
	register usize len = _len;
	static const char* fmts[] = { "match: ", "%lu: ", SLICE_FORMAT, " (len %lu)", "failure: ", (const char*)NULL };
#define ADDSTR(s) do { debug_assert((s)); strncat(str, (s), len); w = strlen((s)); w = w > len ? len : w; ifU(len<=w) { str[len-1] = 0; return w; } len -= w; str += w; fw+=w; } while(0)
	usize fw;
	usize w = strlen(strncpy(str, matched ? fmts[0] 
					: DFLAGSET(flags, FAILURES) ? fmts[4]
					: "", len)); if(len<=w || w == 0) { str[len-1] = 0; return 0; } len -= w; str += w; fw = w;
	if(DFLAGSET(flags, NUMBER)) ADDSTR(fmts[1]);
	if(DFLAGSET(flags, SLICE)) ADDSTR(fmts[2]);
	if(DFLAGSET(flags, LENGTH)) ADDSTR(fmts[3]);
	ADDSTR("\n");
	TRACE("Output string written: %lu, (rlen %lu)", fw, len);
	return fw;
#undef ADDSTR
}

static void _display_normal(FILE* output, dispin_t*pIN input, dispflags_t flags)
{
	bool matched = input->matched;
	slice_t cslice = input->cslice;
	const void* base = input->base;
	usize i = input->index;

#ifdef _DEBUG_MANCALC_OFFSETS
	struct {
		usize start, end;
	} pos = {
		.start = AS(cslice.ptr - base, usize),
	};
	pos.end = pos.start + cslice.len;
#else
	let pos = slice_sted((slice_t[]){ SLICE(AS(cslice.ptr - base, usize), cslice.len)});
#endif
	INFO("Mapped region slice for %lu, pre-transform (at %p): " SLICE_FORMAT ", len: %lu", i+1, base, SLICE_FORMAT_ARGS(&cslice), cslice.len);

	//Honour `flags`
	char fmt[200]; //TODO: Find the realistic max for this.
	fmt[_display_get_fmt(flags, matched, 100, fmt)] = 0;
	fprintf(output, fmt, i+1, pos.start, pos.end, pos.end-pos.start);
} 

void display_result(FILE* output, dispin_t input, dispkind_t how, dispflags_t flags)
{
	flags = flags ?: DISPLAY_FLAGS_DEFAULT;
	output = output ?: stdout;

	TRACE("Outputting as %d to %p with flags 0x%08lx", (int)how, output, (usize)flags);
	switch(how)
	{
		case DISPK_NORMAL:
			_display_normal(output, &input, flags);
			break;
		case DISPK_CSV:
		case DISPK_BINARY:
		case DISPK_INI:
			TODO("display kind %d is unimplemented", (int)how);
		default: COLD_EXPR(FATAL("unknown display kind: %d", (int)how));
	}
}