/**
 * @file grammar.c
 * @brief Implements token and AST leaf construction.
 */

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

#include <akerror.h>
#include <akstdlib.h>

#include <akbasic/error.h>
#include <akbasic/grammar.h>

/* Copy into a leaf's inline identifier/literal buffer, refusing truncation. */
static akerr_ErrorContext *copy_bounded(char *dest, const char *src, const char *what)
{
    PREPARE_ERROR(errctx);

    FAIL_ZERO_RETURN(errctx, (src != NULL), AKERR_NULLPOINTER, "NULL %s", what);
    FAIL_ZERO_RETURN(errctx, (strlen(src) < AKBASIC_MAX_STRING_LENGTH),
		     AKBASIC_ERR_VALUE,
		     "%s of %zu characters exceeds the %d character limit",
		     what, strlen(src), AKBASIC_MAX_STRING_LENGTH - 1);
    strncpy(dest, src, AKBASIC_MAX_STRING_LENGTH - 1);
    dest[AKBASIC_MAX_STRING_LENGTH - 1] = '\0';
    SUCCEED_RETURN(errctx);
}

akerr_ErrorContext *akbasic_token_init(akbasic_Token *obj)
{
    PREPARE_ERROR(errctx);

    FAIL_ZERO_RETURN(errctx, (obj != NULL), AKERR_NULLPOINTER, "NULL token in init");
    obj->tokentype = AKBASIC_TOK_UNDEFINED;
    obj->lineno = 0;
    obj->lexeme[0] = '\0';
    SUCCEED_RETURN(errctx);
}

akerr_ErrorContext *akbasic_leaf_init(akbasic_ASTLeaf *obj, akbasic_LeafType leaftype)
{
    PREPARE_ERROR(errctx);

    FAIL_ZERO_RETURN(errctx, (obj != NULL), AKERR_NULLPOINTER, "NULL leaf in init");
    obj->leaftype = leaftype;
    obj->parent = NULL;
    obj->left = NULL;
    obj->right = NULL;
    obj->expr = NULL;
    obj->identifier[0] = '\0';
    obj->literal_int = 0;
    obj->literal_float = 0.0;
    obj->literal_string[0] = '\0';
    obj->operator_ = AKBASIC_TOK_UNDEFINED;
    SUCCEED_RETURN(errctx);
}

/*
 * Take one leaf from the pool. Recursion in clone_into() is bounded by the pool
 * capacity, so a cyclic tree exhausts the pool and errors rather than running
 * off the stack.
 */
static akerr_ErrorContext *pool_take(akbasic_LeafPool *pool, akbasic_ASTLeaf **dest)
{
    PREPARE_ERROR(errctx);

    FAIL_ZERO_RETURN(errctx, (pool != NULL), AKERR_NULLPOINTER, "NULL leaf pool");
    FAIL_ZERO_RETURN(errctx, (pool->leaves != NULL), AKERR_NULLPOINTER, "Leaf pool has no storage");
    FAIL_ZERO_RETURN(errctx, (pool->next < pool->capacity), AKBASIC_ERR_BOUNDS,
		     "No more leaves available");
    *dest = &pool->leaves[pool->next];
    pool->next += 1;
    SUCCEED_RETURN(errctx);
}

static akerr_ErrorContext *clone_into(akbasic_ASTLeaf *self, akbasic_LeafPool *pool, akbasic_ASTLeaf **dest)
{
    PREPARE_ERROR(errctx);
    akbasic_ASTLeaf *copy = NULL;

    if ( self == NULL ) {
	*dest = NULL;
	SUCCEED_RETURN(errctx);
    }
    PASS(errctx, pool_take(pool, &copy));
    PASS(errctx, akbasic_leaf_init(copy, self->leaftype));
    copy->parent = self->parent;
    copy->literal_int = self->literal_int;
    copy->literal_float = self->literal_float;
    memcpy(copy->literal_string, self->literal_string, sizeof(copy->literal_string));
    memcpy(copy->identifier, self->identifier, sizeof(copy->identifier));
    copy->operator_ = self->operator_;

    PASS(errctx, clone_into(self->left, pool, &copy->left));
    PASS(errctx, clone_into(self->right, pool, &copy->right));
    PASS(errctx, clone_into(self->expr, pool, &copy->expr));

    *dest = copy;
    SUCCEED_RETURN(errctx);
}

akerr_ErrorContext *akbasic_leaf_clone(akbasic_ASTLeaf *self, akbasic_LeafPool *pool, akbasic_ASTLeaf **dest)
{
    PREPARE_ERROR(errctx);

    FAIL_ZERO_RETURN(errctx, (dest != NULL), AKERR_NULLPOINTER, "NULL destination in clone");
    PASS(errctx, clone_into(self, pool, dest));
    SUCCEED_RETURN(errctx);
}

akbasic_ASTLeaf *akbasic_leaf_first_argument(akbasic_ASTLeaf *self)
{
    if ( self == NULL ||
	 self->right == NULL ||
	 self->right->leaftype != AKBASIC_LEAF_ARGUMENTLIST ||
	 self->right->operator_ != AKBASIC_TOK_FUNCTION_ARGUMENT ) {
	return NULL;
    }
    return self->right->right;
}

akbasic_ASTLeaf *akbasic_leaf_first_subscript(akbasic_ASTLeaf *self)
{
    if ( self == NULL ||
	 self->right == NULL ||
	 self->right->leaftype != AKBASIC_LEAF_ARGUMENTLIST ||
	 self->right->operator_ != AKBASIC_TOK_ARRAY_SUBSCRIPT ) {
	return NULL;
    }
    return self->right->right;
}

bool akbasic_leaf_is_identifier(akbasic_ASTLeaf *self)
{
    return (self != NULL &&
	    (self->leaftype == AKBASIC_LEAF_IDENTIFIER ||
	     self->leaftype == AKBASIC_LEAF_IDENTIFIER_INT ||
	     self->leaftype == AKBASIC_LEAF_IDENTIFIER_FLOAT ||
	     self->leaftype == AKBASIC_LEAF_IDENTIFIER_STRING));
}

bool akbasic_leaf_is_literal(akbasic_ASTLeaf *self)
{
    return (self != NULL &&
	    (self->leaftype == AKBASIC_LEAF_LITERAL_INT ||
	     self->leaftype == AKBASIC_LEAF_LITERAL_FLOAT ||
	     self->leaftype == AKBASIC_LEAF_LITERAL_STRING));
}

akerr_ErrorContext *akbasic_leaf_new_comparison(akbasic_ASTLeaf *obj, akbasic_ASTLeaf *left, akbasic_TokenType op, akbasic_ASTLeaf *right)
{
    PREPARE_ERROR(errctx);

    FAIL_ZERO_RETURN(errctx, (obj != NULL), AKERR_NULLPOINTER, "NULL leaf in new_comparison");
    FAIL_ZERO_RETURN(errctx, (left != NULL && right != NULL), AKERR_NULLPOINTER,
		     "nil pointer arguments");
    PASS(errctx, akbasic_leaf_init(obj, AKBASIC_LEAF_COMPARISON));
    obj->left = left;
    obj->right = right;
    switch ( op ) {
    case AKBASIC_TOK_LESS_THAN:
    case AKBASIC_TOK_LESS_THAN_EQUAL:
    case AKBASIC_TOK_NOT_EQUAL:
    case AKBASIC_TOK_GREATER_THAN:
    case AKBASIC_TOK_GREATER_THAN_EQUAL:
	SUCCEED_RETURN(errctx);
    default:
	FAIL_RETURN(errctx, AKBASIC_ERR_SYNTAX, "Invalid operator %d for comparison", (int)op);
    }
}

akerr_ErrorContext *akbasic_leaf_new_binary(akbasic_ASTLeaf *obj, akbasic_ASTLeaf *left, akbasic_TokenType op, akbasic_ASTLeaf *right)
{
    PREPARE_ERROR(errctx);

    FAIL_ZERO_RETURN(errctx, (obj != NULL), AKERR_NULLPOINTER, "NULL leaf in new_binary");
    FAIL_ZERO_RETURN(errctx, (left != NULL && right != NULL), AKERR_NULLPOINTER,
		     "nil pointer arguments");
    PASS(errctx, akbasic_leaf_init(obj, AKBASIC_LEAF_BINARY));
    obj->left = left;
    obj->right = right;
    obj->operator_ = op;
    SUCCEED_RETURN(errctx);
}

akerr_ErrorContext *akbasic_leaf_new_unary(akbasic_ASTLeaf *obj, akbasic_TokenType op, akbasic_ASTLeaf *operand)
{
    PREPARE_ERROR(errctx);

    FAIL_ZERO_RETURN(errctx, (obj != NULL), AKERR_NULLPOINTER, "NULL leaf in new_unary");
    FAIL_ZERO_RETURN(errctx, (operand != NULL), AKERR_NULLPOINTER, "nil pointer arguments");
    PASS(errctx, akbasic_leaf_init(obj, AKBASIC_LEAF_UNARY));
    /*
     * .left, not .right. An argument list chains its arguments through .right,
     * so an operand there is indistinguishable from a second argument: ABS(-9)
     * counted as two and was refused. See the note on the declaration.
     */
    obj->left = operand;
    obj->operator_ = op;
    SUCCEED_RETURN(errctx);
}

akerr_ErrorContext *akbasic_leaf_new_function(akbasic_ASTLeaf *obj, const char *fname, akbasic_ASTLeaf *right)
{
    PREPARE_ERROR(errctx);

    FAIL_ZERO_RETURN(errctx, (obj != NULL), AKERR_NULLPOINTER, "NULL leaf in new_function");
    PASS(errctx, akbasic_leaf_init(obj, AKBASIC_LEAF_FUNCTION));
    obj->right = right;
    obj->operator_ = AKBASIC_TOK_COMMAND;
    PASS(errctx, copy_bounded(obj->identifier, fname, "function name"));
    SUCCEED_RETURN(errctx);
}

akerr_ErrorContext *akbasic_leaf_new_command(akbasic_ASTLeaf *obj, const char *cmdname, akbasic_ASTLeaf *right)
{
    PREPARE_ERROR(errctx);

    FAIL_ZERO_RETURN(errctx, (obj != NULL), AKERR_NULLPOINTER, "NULL leaf in new_command");
    PASS(errctx, akbasic_leaf_init(obj, AKBASIC_LEAF_COMMAND));
    obj->right = right;
    obj->operator_ = AKBASIC_TOK_COMMAND;
    PASS(errctx, copy_bounded(obj->identifier, cmdname, "command name"));
    SUCCEED_RETURN(errctx);
}

akerr_ErrorContext *akbasic_leaf_new_immediate_command(akbasic_ASTLeaf *obj, const char *cmdname, akbasic_ASTLeaf *right)
{
    PREPARE_ERROR(errctx);

    FAIL_ZERO_RETURN(errctx, (obj != NULL), AKERR_NULLPOINTER, "NULL leaf in new_immediate_command");
    PASS(errctx, akbasic_leaf_init(obj, AKBASIC_LEAF_COMMAND_IMMEDIATE));
    obj->right = right;
    obj->operator_ = AKBASIC_TOK_COMMAND_IMMEDIATE;
    PASS(errctx, copy_bounded(obj->identifier, cmdname, "command name"));
    SUCCEED_RETURN(errctx);
}

akerr_ErrorContext *akbasic_leaf_new_branch(akbasic_ASTLeaf *obj, akbasic_ASTLeaf *expr, akbasic_ASTLeaf *trueleaf, akbasic_ASTLeaf *falseleaf)
{
    PREPARE_ERROR(errctx);

    FAIL_ZERO_RETURN(errctx, (obj != NULL), AKERR_NULLPOINTER, "NULL leaf in new_branch");
    FAIL_ZERO_RETURN(errctx, (expr != NULL), AKERR_NULLPOINTER, "nil pointer arguments");
    PASS(errctx, akbasic_leaf_init(obj, AKBASIC_LEAF_BRANCH));
    obj->expr = expr;
    obj->left = trueleaf;
    obj->right = falseleaf;
    SUCCEED_RETURN(errctx);
}

akerr_ErrorContext *akbasic_leaf_new_grouping(akbasic_ASTLeaf *obj, akbasic_ASTLeaf *expr)
{
    PREPARE_ERROR(errctx);

    FAIL_ZERO_RETURN(errctx, (obj != NULL), AKERR_NULLPOINTER, "NULL leaf in new_grouping");
    FAIL_ZERO_RETURN(errctx, (expr != NULL), AKERR_NULLPOINTER, "nil pointer arguments");
    PASS(errctx, akbasic_leaf_init(obj, AKBASIC_LEAF_GROUPING));
    obj->expr = expr;
    SUCCEED_RETURN(errctx);
}

akerr_ErrorContext *akbasic_leaf_new_literal_int(akbasic_ASTLeaf *obj, const char *lexeme)
{
    PREPARE_ERROR(errctx);
    long long value = 0;
    int base = 10;

    FAIL_ZERO_RETURN(errctx, (obj != NULL), AKERR_NULLPOINTER, "NULL leaf in new_literal_int");
    FAIL_ZERO_RETURN(errctx, (lexeme != NULL), AKERR_NULLPOINTER, "NULL lexeme in new_literal_int");
    FAIL_ZERO_RETURN(errctx, (lexeme[0] != '\0'), AKBASIC_ERR_VALUE, "Empty integer literal");

    /*
     * Base 10 unless the lexeme is prefixed `0x`. The reference selects base 8
     * for *any* lexeme starting with '0' (basicgrammar.go:224), so `PRINT 010`
     * printed 8 and `PRINT 08` was a parse error -- TODO.md section 6 item 10.
     * Commodore BASIC has no octal literals, and a leading zero in a listing is
     * padding, not a radix.
     */
    if ( strlen(lexeme) > 2 && strncmp(lexeme, "0x", 2) == 0 ) {
	base = 16;
    }
    PASS(errctx, akbasic_leaf_init(obj, AKBASIC_LEAF_LITERAL_INT));
    PASS(errctx, aksl_strtoll(lexeme, NULL, base, &value));
    obj->literal_int = (int64_t)value;
    SUCCEED_RETURN(errctx);
}

akerr_ErrorContext *akbasic_leaf_new_literal_float(akbasic_ASTLeaf *obj, const char *lexeme)
{
    PREPARE_ERROR(errctx);

    FAIL_ZERO_RETURN(errctx, (obj != NULL), AKERR_NULLPOINTER, "NULL leaf in new_literal_float");
    PASS(errctx, akbasic_leaf_init(obj, AKBASIC_LEAF_LITERAL_FLOAT));
    PASS(errctx, aksl_atof(lexeme, &obj->literal_float));
    SUCCEED_RETURN(errctx);
}

akerr_ErrorContext *akbasic_leaf_new_literal_string(akbasic_ASTLeaf *obj, const char *lexeme)
{
    PREPARE_ERROR(errctx);

    FAIL_ZERO_RETURN(errctx, (obj != NULL), AKERR_NULLPOINTER, "NULL leaf in new_literal_string");
    PASS(errctx, akbasic_leaf_init(obj, AKBASIC_LEAF_LITERAL_STRING));
    PASS(errctx, copy_bounded(obj->literal_string, lexeme, "string literal"));
    SUCCEED_RETURN(errctx);
}

akerr_ErrorContext *akbasic_leaf_new_identifier(akbasic_ASTLeaf *obj, akbasic_LeafType leaftype, const char *lexeme)
{
    PREPARE_ERROR(errctx);

    FAIL_ZERO_RETURN(errctx, (obj != NULL), AKERR_NULLPOINTER, "NULL leaf in new_identifier");
    PASS(errctx, akbasic_leaf_init(obj, leaftype));
    PASS(errctx, copy_bounded(obj->identifier, lexeme, "identifier"));
    SUCCEED_RETURN(errctx);
}

static const char *operator_to_str(akbasic_TokenType op)
{
    switch ( op ) {
    case AKBASIC_TOK_EQUAL:			return "=";
    case AKBASIC_TOK_LESS_THAN:			return "<";
    case AKBASIC_TOK_GREATER_THAN:		return ">";
    case AKBASIC_TOK_LESS_THAN_EQUAL:		return "<=";
    case AKBASIC_TOK_GREATER_THAN_EQUAL:	return ">=";
    case AKBASIC_TOK_NOT_EQUAL:			return "<>";
    case AKBASIC_TOK_PLUS:			return "+";
    case AKBASIC_TOK_MINUS:			return "-";
    case AKBASIC_TOK_STAR:			return "*";
    case AKBASIC_TOK_LEFT_SLASH:		return "/";
    case AKBASIC_TOK_CARAT:			return "^";
    case AKBASIC_TOK_NOT:			return "NOT";
    case AKBASIC_TOK_AND:			return "AND";
    case AKBASIC_TOK_OR:			return "OR";
    default:					return "";
    }
}

akerr_ErrorContext *akbasic_leaf_to_string(akbasic_ASTLeaf *self, char *dest, size_t len)
{
    PREPARE_ERROR(errctx);
    char sub1[AKBASIC_MAX_STRING_LENGTH];
    char sub2[AKBASIC_MAX_STRING_LENGTH];

    FAIL_ZERO_RETURN(errctx, (self != NULL), AKERR_NULLPOINTER, "NULL leaf in to_string");
    FAIL_ZERO_RETURN(errctx, (dest != NULL), AKERR_NULLPOINTER, "NULL destination in to_string");
    FAIL_ZERO_RETURN(errctx, (len > 0), AKBASIC_ERR_BOUNDS, "Zero-length destination in to_string");

    switch ( self->leaftype ) {
    case AKBASIC_LEAF_LITERAL_INT:
	snprintf(dest, len, "%" PRId64, self->literal_int);
	break;
    case AKBASIC_LEAF_LITERAL_FLOAT:
	snprintf(dest, len, "%f", self->literal_float);
	break;
    case AKBASIC_LEAF_LITERAL_STRING:
	snprintf(dest, len, "%s", self->literal_string);
	break;
    case AKBASIC_LEAF_IDENTIFIER_INT:
    case AKBASIC_LEAF_IDENTIFIER_FLOAT:
    case AKBASIC_LEAF_IDENTIFIER_STRING:
    case AKBASIC_LEAF_IDENTIFIER:
	snprintf(dest, len, "%s", self->identifier);
	break;
    case AKBASIC_LEAF_IDENTIFIER_STRUCT:
	snprintf(dest, len, "NOT IMPLEMENTED");
	break;
    case AKBASIC_LEAF_UNARY:
	PASS(errctx, akbasic_leaf_to_string(self->left, sub1, sizeof(sub1)));
	snprintf(dest, len, "(%s %s)", operator_to_str(self->operator_), sub1);
	break;
    case AKBASIC_LEAF_BINARY:
	PASS(errctx, akbasic_leaf_to_string(self->left, sub1, sizeof(sub1)));
	PASS(errctx, akbasic_leaf_to_string(self->right, sub2, sizeof(sub2)));
	snprintf(dest, len, "(%s %s %s)", operator_to_str(self->operator_), sub1, sub2);
	break;
    case AKBASIC_LEAF_GROUPING:
	PASS(errctx, akbasic_leaf_to_string(self->expr, sub1, sizeof(sub1)));
	snprintf(dest, len, "(group %s)", sub1);
	break;
    case AKBASIC_LEAF_COMMAND:
    case AKBASIC_LEAF_COMMAND_IMMEDIATE:
    case AKBASIC_LEAF_FUNCTION:
	/*
	 * The reference falls through to Go's %+v struct dump here, which has no
	 * useful C equivalent. Print something a test can assert on instead.
	 */
	snprintf(dest, len, "(%s)", self->identifier);
	break;
    default:
	snprintf(dest, len, "(leaf %d)", (int)self->leaftype);
	break;
    }
    SUCCEED_RETURN(errctx);
}