/**
 * @file parser_commands.c
 * @brief Tests the verbs that carry their own parse path.
 */

#include "harness.h"

static void expect_command(const char *line, akbasic_LeafType wanttype, const char *wantname)
{
    akbasic_ASTLeaf *leaf = NULL;
    akerr_ErrorContext *e = NULL;

    e = harness_parse(line, &leaf);
    if ( e != NULL ) {
	fprintf(stderr, "FAIL: \"%s\" did not parse: %s\n", line, e->message);
	akbasic_test_failures += 1;
	test_discard_error(e);
	return;
    }
    TEST_REQUIRE(leaf != NULL, "\"%s\" produced no leaf", line);
    if ( leaf == NULL ) {
	return;
    }
    TEST_REQUIRE_INT(leaf->leaftype, wanttype);
    if ( wantname != NULL ) {
	TEST_REQUIRE_STR(leaf->identifier, wantname);
    }
}

static void expect_parse_error(const char *line)
{
    akbasic_ASTLeaf *leaf = NULL;
    akerr_ErrorContext *e = NULL;

    e = harness_parse(line, &leaf);
    TEST_REQUIRE(e != NULL, "\"%s\" should not have parsed", line);
    if ( e != NULL ) {
	test_discard_error(e);
    }
}

/**
 * @brief Parse a whole line and report how many statements came out of it.
 *
 * The statement loop the runtime uses, in miniature: parse until the token
 * stream is spent, skipping the NULL leaf that an empty statement produces.
 */
static int count_statements(const char *line)
{
    akbasic_Parser parser;
    akbasic_ASTLeaf *leaf = NULL;
    akerr_ErrorContext *e = NULL;
    int count = 0;

    e = akbasic_scanner_zero(&HARNESS_RUNTIME);
    if ( e == NULL ) {
	e = akbasic_scanner_scan(&HARNESS_RUNTIME, line, NULL, 0);
    }
    if ( e == NULL ) {
	e = akbasic_parser_init(&parser, &HARNESS_RUNTIME);
    }
    while ( e == NULL && !akbasic_parser_is_at_end(&parser) ) {
	leaf = NULL;
	e = akbasic_parser_parse(&parser, &leaf);
	if ( e == NULL && leaf != NULL ) {
	    count += 1;
	}
    }
    if ( e != NULL ) {
	fprintf(stderr, "FAIL: \"%s\" did not parse: %s\n", line, e->message);
	akbasic_test_failures += 1;
	test_discard_error(e);
	return -1;
    }
    return count;
}

int main(void)
{
    akbasic_ASTLeaf *leaf = NULL;

    TEST_REQUIRE_OK(harness_start(NULL));

    /* Plain verbs with an expression rval. */
    expect_command("PRINT 1", AKBASIC_LEAF_COMMAND, "PRINT");
    expect_command("GOTO 100", AKBASIC_LEAF_COMMAND, "GOTO");
    expect_command("GOSUB 100", AKBASIC_LEAF_COMMAND, "GOSUB");

    /* A verb with no rval at all must not fail. */
    expect_command("RETURN", AKBASIC_LEAF_COMMAND, "RETURN");
    expect_command("STOP", AKBASIC_LEAF_COMMAND, "STOP");

    /* Immediate commands get their own leaf type. */
    expect_command("QUIT", AKBASIC_LEAF_COMMAND_IMMEDIATE, "QUIT");
    expect_command("LIST", AKBASIC_LEAF_COMMAND_IMMEDIATE, "LIST");
    expect_command("RUN", AKBASIC_LEAF_COMMAND_IMMEDIATE, "RUN");

    /* Verbs with their own parse path. */
    expect_command("LABEL LOOPTOP", AKBASIC_LEAF_COMMAND, "LABEL");
    expect_command("DIM A#(5)", AKBASIC_LEAF_COMMAND, "DIM");
    expect_command("DATA 1, 2, 3", AKBASIC_LEAF_COMMAND, "DATA");
    /*
     * A negated literal is one. `DATA -5` used to be refused here and only here:
     * READ scans the source text directly and returned the -5 intact, so the
     * value was right and reaching the *statement* raised "Expected literal" --
     * which is a table of coordinates or velocities failing on the line after
     * it. TODO.md section 9 item 8.
     */
    expect_command("DATA -5", AKBASIC_LEAF_COMMAND, "DATA");
    expect_command("DATA -1, 2, -3.5", AKBASIC_LEAF_COMMAND, "DATA");
    /* Only over a literal, though: a negated variable is still a mistake. */
    expect_parse_error("DATA -A#");

    /*
     * `GRAPHIC CLR` is documented in two chapters and used to be refused: CLR is
     * a verb of its own, so the generic arglist path scanned it as a command
     * token rather than as this verb's keyword argument. TODO.md section 9 item
     * 7. It becomes mode 5, which the exec handler already treats as exactly
     * this, so both spellings are one statement.
     */
    expect_command("GRAPHIC CLR", AKBASIC_LEAF_COMMAND, "GRAPHIC");
    expect_command("GRAPHIC 1, 1", AKBASIC_LEAF_COMMAND, "GRAPHIC");
    expect_command("READ A#, B#", AKBASIC_LEAF_COMMAND, "READ");
    expect_command("POKE 100, 1", AKBASIC_LEAF_COMMAND, "POKE");
    expect_command("INPUT \"NAME? \" A$", AKBASIC_LEAF_COMMAND, "INPUT");

    /* LET parses as a bare assignment. */
    expect_command("LET A# = 1", AKBASIC_LEAF_BINARY, NULL);

    /* IF produces a BRANCH, not a COMMAND. */
    expect_command("IF 1 == 1 THEN PRINT 1", AKBASIC_LEAF_BRANCH, NULL);
    TEST_REQUIRE_OK(harness_parse("IF 1 == 1 THEN PRINT 1 ELSE PRINT 2", &leaf));
    TEST_REQUIRE(leaf != NULL && leaf->left != NULL && leaf->right != NULL,
		 "IF ... THEN ... ELSE must fill both branches");

    /* FOR installs a loop environment and returns the assignment. */
    {
	akbasic_Environment *before = HARNESS_RUNTIME.environment;
	TEST_REQUIRE_OK(harness_parse("FOR I# = 1 TO 5", &leaf));
	TEST_REQUIRE(HARNESS_RUNTIME.environment != before,
		     "FOR must install a new environment");
	TEST_REQUIRE(HARNESS_RUNTIME.environment->forToLeaf != NULL,
		     "FOR must record its TO expression");
	TEST_REQUIRE(HARNESS_RUNTIME.environment->forStepLeaf != NULL,
		     "FOR must default its STEP to 1");
	TEST_REQUIRE_OK(akbasic_runtime_prev_environment(&HARNESS_RUNTIME));
    }
    {
	akbasic_Environment *before = HARNESS_RUNTIME.environment;
	TEST_REQUIRE_OK(harness_parse("FOR I# = 1 TO 10 STEP 2", &leaf));
	TEST_REQUIRE(HARNESS_RUNTIME.environment != before, "FOR STEP must install an environment");
	TEST_REQUIRE_OK(akbasic_runtime_prev_environment(&HARNESS_RUNTIME));
    }

    /* Malformed FOR is rejected at parse time. */
    expect_parse_error("FOR I# = 1");
    expect_parse_error("FOR I# = 1 TO 5 STEP");
    expect_parse_error("FOR 1 TO 5");

    /* Other malformed forms. */
    expect_parse_error("IF 1 == 1 PRINT 1");
    expect_parse_error("LABEL 5");
    expect_parse_error("READ 1");
    expect_parse_error("DATA A#");

    /*
     * Colons separate statements. The token has existed since the scanner was
     * written and nothing consumed it, so every one of these was a parse error
     * until the statement loop learned to skip past it -- TODO.md section 4.
     */
    TEST_REQUIRE_INT(count_statements("PRINT 1"), 1);
    TEST_REQUIRE_INT(count_statements("PRINT 1 : PRINT 2"), 2);
    TEST_REQUIRE_INT(count_statements("A# = 1 : B# = 2 : PRINT A# + B#"), 3);

    /* An empty statement is not an error, and does not count as one. */
    TEST_REQUIRE_INT(count_statements("PRINT 1 :"), 1);
    TEST_REQUIRE_INT(count_statements(": PRINT 1"), 1);
    TEST_REQUIRE_INT(count_statements("PRINT 1 :: PRINT 2"), 2);
    TEST_REQUIRE_INT(count_statements(":"), 0);
    TEST_REQUIRE_INT(count_statements(":::"), 0);

    /*
     * A verb that takes no rval stops at the separator rather than trying to
     * parse one out of it.
     */
    TEST_REQUIRE_INT(count_statements("PRINT : PRINT 2"), 2);

    /*
     * IF takes exactly one statement for each arm; the rest of the line arrives
     * at the statement loop as ordinary statements, and it is the *runtime* that
     * decides whether to run them. That split is asserted end to end in
     * tests/language/statements/multiple_per_line.bas, because it is a question
     * about execution rather than about the shape of the tree.
     */
    TEST_REQUIRE_INT(count_statements("IF 1 == 1 THEN PRINT 1 : PRINT 2"), 2);
    TEST_REQUIRE_INT(count_statements("IF 1 == 1 THEN PRINT 1 ELSE PRINT 2 : PRINT 3"), 2);

    harness_stop();
    return akbasic_test_failures;
}