/*
 * ecgen, tool for generating Elliptic curve domain parameters
 * Copyright (C) 2017 J08nY
 */
#include "cli.h"
#include <string.h>

char doc[] =
	"ecgen, tool for generating Elliptic curve domain parameters.\v(C) 2017 "
		"Eastern Seaboard Phishing Authority";
char args_doc[] = "bits";

enum opt_keys {
	OPT_DATADIR = 'd',
	OPT_PRIME = 'p',
	OPT_RANDOM = 'r',
	OPT_SEED = 's',
	OPT_INVALID = 'i',
	OPT_ORDER = 'n',
	OPT_KOBLITZ = 'k',
	OPT_OUTPUT = 'o',
	OPT_INPUT = 'f',
	OPT_APPEND = 'a',
	OPT_FP = 1,
	OPT_F2M = 2,
};

// clang-format off
struct argp_option options[] = {
	// Field specification
	{"fp",         OPT_FP,      0,       0,                  "Prime field."},
	{"f2m",        OPT_F2M,     0,       0,                  "Binary field."},
	// Curve specification
	{"random", OPT_RANDOM,  0,       0,                  "Generate a random curve."},
	{"prime",      OPT_PRIME,   0,       0,                  "Generate a curve with prime order."},
	{"seed",       OPT_SEED,    "SEED", OPTION_ARG_OPTIONAL, "Generate a curve from SEED (ANSI X9.62 verifiable procedure)."},
	{"invalid",    OPT_INVALID, 0,       0,                  "Generate a set of invalid curves (for a given curve)."},
	{"order",      OPT_ORDER,   "ORDER", 0,                  "Generate a curve with given order (using Complex Multiplication)."},
	{"koblitz",    OPT_KOBLITZ, 0,       0,                  "Generate a Koblitz curve."},
	// Other
	{"data-dir",   OPT_DATADIR, "DIR",   0,                  "PARI/GP data directory (containing seadata package)."},
	{"input",      OPT_INPUT,   "FILE",  0,                  "Input from file."},
	{"output",     OPT_OUTPUT,  "FILE",  0,                  "Output into file. Overwrites any existing file!"},
	{"append",     OPT_APPEND,  0,       0,                  "Append to output file (don't overwrite)."},
	{0}};
// clang-format on

error_t parse_opt(int key, char *arg, struct argp_state *state) {
	struct config_t *cfg = state->input;

	switch (key) {
		case OPT_DATADIR:
			cfg->datadir = arg;
			break;
		case OPT_INPUT:
			cfg->input = arg;
			break;
		case OPT_OUTPUT:
			cfg->output = arg;
			break;
		case OPT_APPEND:
			cfg->append = true;
			break;
		case OPT_RANDOM:
			cfg->random = true;
			break;
		case OPT_PRIME:
			cfg->prime = true;
			break;
		case OPT_INVALID:
			cfg->invalid = true;
			break;
		case OPT_ORDER:
			cfg->cm = true;
			if (arg) {
				cfg->order = arg;
			}
			break;
		case OPT_KOBLITZ:
			cfg->koblitz = true;
			break;
		case OPT_SEED:
			cfg->from_seed = true;
			if (arg) {
				// ANSI X9.62 specifies seed as at least 160 bits in length.
				if (strlen(arg) < 20) {
					argp_failure(
						state, 1, 0,
						"SEED must be at least 160 bits(20 characters).");
				}
				cfg->seed = arg;
			}
			break;
		case OPT_FP:
			cfg->field = FIELD_PRIME;
			cfg->prime_field = true;
			break;
		case OPT_F2M:
			cfg->field = FIELD_BINARY;
			cfg->binary_field = true;
			break;
		case ARGP_KEY_ARG:
			if (state->arg_num >= 1) {
				argp_usage(state);
			}

			cfg->bits = strtol(arg, NULL, 10);
			break;
		case ARGP_KEY_END:
			// validate all option states here.
			// Only one field
			if (!cfg->prime_field && !cfg->binary_field) {
				argp_failure(state, 1, 0,
							 "Specify field type, prime or binary, with --fp / "
								 "--f2m(but not both).");
			}
			// Invalid is not prime or seed or exhaustive by definition.
			if (cfg->invalid && (cfg->prime || cfg->from_seed || cfg->random)) {
				// not seed, not prime, not exhaustive
				argp_failure(state, 1, 0,
							 "Invalid curve generation can not generate curves "
								 "from seed, exhaustive or prime order.");
			}
			if (cfg->cm && (cfg->prime || cfg->from_seed || cfg->invalid)) {
				argp_failure(state, 1, 0,
							 "Fixed order curve generation can not generate "
								 "curves from seed, or invalid curves. Prime order "
								 "also doesn't make sense if the given one isn't "
								 "prime.");
			}
			break;
		case ARGP_KEY_NO_ARGS:
			argp_usage(state);
			break;
		default:
			return ARGP_ERR_UNKNOWN;
	}
	return 0;
}