#include <stdint.h>
#include <stddef.h>

#include "libbase64.h"
#include "codecs.h"

const uint8_t
plain32_base64_table_enc[] =
	"ABCDEFGHIJKLMNOPQRSTUVWXYZ"
	"abcdefghijklmnopqrstuvwxyz"
	"0123456789+/";

// In the lookup table below, note that the value for '=' (character 61) is
// 254, not 255. This character is used for in-band signaling of the end of
// the datastream, and we will use that later. The characters A-Z, a-z, 0-9
// and + / are mapped to their "decoded" values. The other bytes all map to
// the value 255, which flags them as "invalid input".

const uint8_t
plain32_base64_table_dec[] =
{
	255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255,		//   0..15
	255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255,		//  16..31
	255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255,  62, 254,  62, 255,  63,		//  32..47
	 52,  53,  54,  55,  56,  57,  58,  59,  60,  61, 255, 255, 255, 254, 255, 255,		//  48..63
	255,   0,   1,   2,   3,   4,   5,   6,   7,   8,   9,  10,  11,  12,  13,  14,		//  64..79
	 15,  16,  17,  18,  19,  20,  21,  22,  23,  24,  25, 255, 255, 255, 255,  63,		//  80..95
	255,  26,  27,  28,  29,  30,  31,  32,  33,  34,  35,  36,  37,  38,  39,  40,		//  96..111
	 41,  42,  43,  44,  45,  46,  47,  48,  49,  50,  51, 255, 255, 255, 255, 255,		// 112..127
	255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255,		// 128..143
	255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255,
	255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255,
	255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255,
	255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255,
	255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255,
	255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255,
	255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255,
};

void
plain32_base64_stream_encode_init (struct plain32_base64_state *state)
{
	state->eof = 0;
	state->bytes = 0;
	state->carry = 0;
}

void
plain32_base64_stream_encode_final
	( struct plain32_base64_state	*state
	, char			*out
	, size_t		*outlen
	)
{
	uint8_t *o = (uint8_t *)out;

	if (state->bytes == 1) {
		*o++ = plain32_base64_table_enc[state->carry];
		*o++ = '=';
		*o++ = '=';
		*outlen = 3;
		return;
	}
	if (state->bytes == 2) {
		*o++ = plain32_base64_table_enc[state->carry];
		*o++ = '=';
		*outlen = 2;
		return;
	}
	*outlen = 0;
}

void
plain32_base64_stream_decode_init (struct plain32_base64_state *state)
{
	state->eof = 0;
	state->bytes = 0;
	state->carry = 0;
}

void
plain32_base64_encode
	( const char	*src
	, size_t	 srclen
	, char		*out
	, size_t	*outlen
	)
{
	size_t s;
	size_t t;
	struct plain32_base64_state state;

	// Init the stream reader:
	plain32_base64_stream_encode_init(&state);

	// Feed the whole string to the stream reader:
	plain32_base64_stream_encode(&state, src, srclen, out, &s);

	// Finalize the stream by writing trailer if any:
	plain32_base64_stream_encode_final(&state, out + s, &t);

	// Final output length is stream length plus tail:
	*outlen = s + t;
}

int
plain32_base64_decode
	( const char	*src
	, size_t	 srclen
	, char		*out
	, size_t	*outlen
	)
{
	struct plain32_base64_state state;

	// Init the stream reader:
	plain32_base64_stream_decode_init(&state);

	// Feed the whole string to the stream reader:
	return plain32_base64_stream_decode(&state, src, srclen, out, outlen);
}