#include "ctx.h"
#include "node.h"

#include <blue/object/string.h>
#include <ivy/lang/operator.h>
#include <ivy/lang/lex.h>
#include <stdio.h>

enum expr_end {
	EXPR_END_NONE = 0,
	/* arithmetic expressions, terminated with a dot (.) */
	EXPR_END_DOT,
	/* keyword expressions (if-else, while/for loops, match, etc), terminated with the end keyword. */
	EXPR_END_KEYWORD,
};

enum expr_part {
	EXPR_NONE = 0,
	EXPR_OPERATOR,
	EXPR_OPERAND,
};

struct expr_parser_state {
	struct parser_state s_base;
	enum expr_end s_end;
	enum ivy_keyword s_type;
	unsigned int s_prev_tok;
	enum expr_part s_prev_part;
	b_queue s_operand_queue;
	b_queue s_operator_stack;
};

static enum ivy_status add_child(
	struct ivy_ast_node *parent, struct ivy_ast_node *child)
{
	struct ivy_ast_expr_node *expr = (struct ivy_ast_expr_node *)parent;

	if (!expr->n_child) {
		expr->n_child = child;
		return IVY_OK;
	}

	return IVY_ERR_NOT_SUPPORTED;
}

static void set_previous(struct expr_parser_state *state, struct ivy_token *tok)
{
	switch (tok->t_type) {
	case IVY_TOK_SYMBOL:
		state->s_prev_tok = tok->t_symbol;
		state->s_prev_part = EXPR_OPERATOR;
		break;
	case IVY_TOK_KEYWORD:
		state->s_prev_tok = tok->t_keyword;
		state->s_prev_part = EXPR_OPERATOR;
		break;
	default:
		state->s_prev_tok = tok->t_type;
		state->s_prev_part = EXPR_OPERAND;
		break;
	}
}

static void print_token(struct ivy_token *tok)
{
	switch (tok->t_type) {
	case IVY_TOK_IDENT:
		printf("%s", tok->t_str);
		break;
	case IVY_TOK_INT:
		printf("%llu", tok->t_int);
		break;
	case IVY_TOK_DOUBLE:
		printf("%.2lf", tok->t_double);
		break;
	case IVY_TOK_SYMBOL:
		printf("%s", ivy_symbol_to_string(tok->t_symbol));
		break;
	case IVY_TOK_KEYWORD:
		printf("%s", ivy_keyword_to_string(tok->t_keyword));
		break;
	case IVY_TOK_STRING:
		printf("\"%s\"", tok->t_str);
		break;
	default:
		printf("<token>");
		break;
	}
}

static enum ivy_status finalise_expr(struct expr_parser_state *state)
{
	b_queue_iterator it = {0};

	int i = 0;
	b_queue_foreach (&it, &state->s_operand_queue) {
		struct ivy_token *operand = b_unbox(struct ivy_token, it.entry, t_entry);

		if (i > 0) {
			printf(" ");
		}

		print_token(operand);
		i++;
	}

	b_queue_foreach (&it, &state->s_operator_stack) {
		struct ivy_token *operator = b_unbox(struct ivy_token, it.entry, t_entry);

		if (i > 0) {
			printf(" ");
		}

		print_token(operator);
		i++;
	}

	printf("\n");
	return IVY_OK;
}

static struct token_parse_result parse_ident(
	struct ivy_parser *ctx, struct ivy_token *tok)
{
	struct expr_parser_state *state
		= parser_get_state(ctx, struct expr_parser_state);

	if (state->s_end == EXPR_END_NONE) {
		state->s_end = EXPR_END_DOT;
	}

	b_queue_push_back(&state->s_operand_queue, &tok->t_entry);
	set_previous(state, tok);

	return PARSE_RESULT(IVY_OK, 0);
}

static struct token_parse_result parse_atom(
	struct ivy_parser *ctx, struct ivy_token *tok)
{
	struct expr_parser_state *state
		= parser_get_state(ctx, struct expr_parser_state);

	if (state->s_end == EXPR_END_NONE) {
		state->s_end = EXPR_END_DOT;
	}

	b_queue_push_back(&state->s_operand_queue, &tok->t_entry);
	set_previous(state, tok);

	return PARSE_RESULT(IVY_OK, 0);
}

static struct token_parse_result parse_string(
	struct ivy_parser *ctx, struct ivy_token *tok)
{
	struct expr_parser_state *state
		= parser_get_state(ctx, struct expr_parser_state);

	if (state->s_end == EXPR_END_NONE) {
		state->s_end = EXPR_END_DOT;
	}

	b_queue_push_back(&state->s_operand_queue, &tok->t_entry);
	set_previous(state, tok);
	return PARSE_RESULT(IVY_OK, 0);
}

static struct token_parse_result parse_str_start(
	struct ivy_parser *ctx, struct ivy_token *tok)
{
	return PARSE_RESULT(IVY_ERR_IO_FAILURE, 0);
}

static struct token_parse_result parse_str_end(
	struct ivy_parser *ctx, struct ivy_token *tok)
{
	return PARSE_RESULT(IVY_ERR_IO_FAILURE, 0);
}

static struct token_parse_result parse_label(
	struct ivy_parser *ctx, struct ivy_token *tok)
{
	return PARSE_RESULT(IVY_ERR_IO_FAILURE, 0);
}

static struct token_parse_result parse_int(
	struct ivy_parser *ctx, struct ivy_token *tok)
{
	struct expr_parser_state *state
		= parser_get_state(ctx, struct expr_parser_state);

	if (state->s_end == EXPR_END_NONE) {
		state->s_end = EXPR_END_DOT;
	}

	b_queue_push_back(&state->s_operand_queue, &tok->t_entry);
	set_previous(state, tok);

	return PARSE_RESULT(IVY_OK, 0);
}

static struct token_parse_result parse_double(
	struct ivy_parser *ctx, struct ivy_token *tok)
{
	struct expr_parser_state *state
		= parser_get_state(ctx, struct expr_parser_state);

	if (state->s_end == EXPR_END_NONE) {
		state->s_end = EXPR_END_DOT;
	}

	b_queue_push_back(&state->s_operand_queue, &tok->t_entry);
	set_previous(state, tok);
	
	return PARSE_RESULT(IVY_OK, 0);
}

static struct ivy_operator *get_operator(struct ivy_token *tok)
{
	switch (tok->t_type) {
	case IVY_TOK_KEYWORD:
		return ivy_operator_get(tok->t_keyword);
	case IVY_TOK_SYMBOL:
		return ivy_operator_get(tok->t_symbol);
	default:
		return NULL;
	}
}

static struct token_parse_result parse_symbol(
	struct ivy_parser *ctx, struct ivy_token *tok)
{
	struct expr_parser_state *state
		= parser_get_state(ctx, struct expr_parser_state);

	if (state->s_end != EXPR_END_DOT) {
		return PARSE_RESULT(IVY_ERR_BAD_SYNTAX, 0);
	}

	struct ivy_operator *op = ivy_operator_get(tok->t_symbol);
	if (!op) {
		return PARSE_RESULT(IVY_ERR_BAD_SYNTAX, 0);
	}

	while (true) {
		b_queue_entry *top_entry = b_queue_last(&state->s_operator_stack);

		if (!top_entry) {
			break;
		}

		struct ivy_token *top = b_unbox(struct ivy_token, top_entry, t_entry);
		if (ivy_token_is_symbol(top, IVY_SYM_LEFT_PAREN)) {
			break;
		}

		struct ivy_operator *top_op = get_operator(top);
		if (top_op->op_precedence < op->op_precedence) {
			break;
		}

		if (top_op->op_precedence == op->op_precedence && op->op_associativity != IVY_ASSOCIATIVITY_LEFT) {
			break;
		}

		b_queue_delete(&state->s_operator_stack, top_entry);
		b_queue_push_back(&state->s_operand_queue, top_entry);
	}

	b_queue_push_back(&state->s_operator_stack, &tok->t_entry);
	set_previous(state, tok);

	return PARSE_RESULT(IVY_OK, 0);
}

static struct token_parse_result parse_left_paren(
	struct ivy_parser *ctx, struct ivy_token *tok)
{
	struct expr_parser_state *state
		= parser_get_state(ctx, struct expr_parser_state);

	if (state->s_end == EXPR_END_NONE) {
		state->s_end = EXPR_END_DOT;
	}

	b_queue_push_back(&state->s_operator_stack, &tok->t_entry);
	set_previous(state, tok);
	
	return PARSE_RESULT(IVY_OK, 0);
}

static struct token_parse_result parse_right_paren(
	struct ivy_parser *ctx, struct ivy_token *tok)
{
	return PARSE_RESULT(IVY_OK, 0);
}

static struct token_parse_result parse_if(
	struct ivy_parser *ctx, struct ivy_token *tok)
{
	struct expr_parser_state *state
		= parser_get_state(ctx, struct expr_parser_state);

	if (state->s_end == EXPR_END_NONE) {
		state->s_end = EXPR_END_KEYWORD;
	}

	return PARSE_RESULT(IVY_OK, 0);
}

static struct token_parse_result parse_else(
	struct ivy_parser *ctx, struct ivy_token *tok)
{
	return PARSE_RESULT(IVY_ERR_IO_FAILURE, 0);
}

static struct token_parse_result parse_end(
	struct ivy_parser *ctx, struct ivy_token *tok)
{
	return PARSE_RESULT(IVY_ERR_IO_FAILURE, 0);
}

static struct token_parse_result parse_while(
	struct ivy_parser *ctx, struct ivy_token *tok)
{
	return PARSE_RESULT(IVY_ERR_IO_FAILURE, 0);
}

static struct token_parse_result parse_for(
	struct ivy_parser *ctx, struct ivy_token *tok)
{
	return PARSE_RESULT(IVY_ERR_IO_FAILURE, 0);
}

static struct token_parse_result parse_match(
	struct ivy_parser *ctx, struct ivy_token *tok)
{
	return PARSE_RESULT(IVY_ERR_IO_FAILURE, 0);
}

static struct token_parse_result parse_try(
	struct ivy_parser *ctx, struct ivy_token *tok)
{
	return PARSE_RESULT(IVY_ERR_IO_FAILURE, 0);
}

static struct token_parse_result parse_catch(
	struct ivy_parser *ctx, struct ivy_token *tok)
{
	return PARSE_RESULT(IVY_ERR_IO_FAILURE, 0);
}

static struct token_parse_result parse_throw(
	struct ivy_parser *ctx, struct ivy_token *tok)
{
	return PARSE_RESULT(IVY_ERR_IO_FAILURE, 0);
}

static struct token_parse_result parse_understands(
	struct ivy_parser *ctx, struct ivy_token *tok)
{
	return PARSE_RESULT(IVY_ERR_IO_FAILURE, 0);
}

static struct token_parse_result parse_in(
	struct ivy_parser *ctx, struct ivy_token *tok)
{
	return PARSE_RESULT(IVY_ERR_IO_FAILURE, 0);
}

static struct token_parse_result parse_do(
	struct ivy_parser *ctx, struct ivy_token *tok)
{
	return PARSE_RESULT(IVY_ERR_IO_FAILURE, 0);
}

static struct token_parse_result parse_is(
	struct ivy_parser *ctx, struct ivy_token *tok)
{
	return PARSE_RESULT(IVY_ERR_IO_FAILURE, 0);
}

static struct token_parse_result parse_and(
	struct ivy_parser *ctx, struct ivy_token *tok)
{
	return PARSE_RESULT(IVY_ERR_IO_FAILURE, 0);
}

static struct token_parse_result parse_or(
	struct ivy_parser *ctx, struct ivy_token *tok)
{
	return PARSE_RESULT(IVY_ERR_IO_FAILURE, 0);
}

static struct token_parse_result parse_not(
	struct ivy_parser *ctx, struct ivy_token *tok)
{
	return PARSE_RESULT(IVY_ERR_IO_FAILURE, 0);
}

static struct token_parse_result parse_bang(
	struct ivy_parser *ctx, struct ivy_token *tok)
{
	struct expr_parser_state *state
		= parser_get_state(ctx, struct expr_parser_state);

	if (state->s_end != EXPR_END_DOT) {
		return PARSE_RESULT(IVY_ERR_BAD_SYNTAX, 0);
	}

	enum ivy_status status = finalise_expr(state);

	parser_pop_state(ctx, STATE_ADD_NODE_TO_PARENT);
	return PARSE_RESULT(status, PARSE_REPEAT_TOKEN);
}

static struct token_parse_result parse_dot(
	struct ivy_parser *ctx, struct ivy_token *tok)
{
	struct expr_parser_state *state
		= parser_get_state(ctx, struct expr_parser_state);

	if (state->s_end != EXPR_END_DOT) {
		return PARSE_RESULT(IVY_ERR_BAD_SYNTAX, 0);
	}

	enum ivy_status status = finalise_expr(state);

	parser_pop_state(ctx, STATE_ADD_NODE_TO_PARENT);
	return PARSE_RESULT(status, 0);
}

struct ast_node_type expr_node_ops = {
	.n_add_child = add_child,
	.n_state_size = sizeof(struct expr_parser_state),
	.n_node_size = sizeof(struct ivy_ast_expr_node),
        .n_token_parsers = {
		[IVY_TOK_IDENT] = parse_ident,
		[IVY_TOK_ATOM] = parse_atom,
		[IVY_TOK_STRING] = parse_string,
		[IVY_TOK_STR_START] = parse_str_start,
		[IVY_TOK_STR_END] = parse_str_end,
		[IVY_TOK_LABEL] = parse_label,
		[IVY_TOK_INT] = parse_int,
		[IVY_TOK_DOUBLE] = parse_double,
		[IVY_TOK_SYMBOL] = parse_symbol,
	},
	.n_symbol_parsers = {
		[IVY_SYM_BANG] = parse_bang,
		[IVY_SYM_DOT] = parse_dot,
		[IVY_SYM_LEFT_PAREN] = parse_left_paren,
		[IVY_SYM_RIGHT_PAREN] = parse_right_paren,
	},
	.n_keyword_parsers = {
		[IVY_KW_IF] = parse_if,
		[IVY_KW_ELSE] = parse_else,
		[IVY_KW_END] = parse_end,
		[IVY_KW_WHILE] = parse_while,
		[IVY_KW_FOR] = parse_for,
		[IVY_KW_MATCH] = parse_match,
		[IVY_KW_TRY] = parse_try,
		[IVY_KW_CATCH] = parse_catch,
		[IVY_KW_THROW] = parse_throw,
		[IVY_KW_UNDERSTANDS] = parse_understands,
		[IVY_KW_IN] = parse_in,
		[IVY_KW_DO] = parse_do,
		[IVY_KW_IS] = parse_is,
		[IVY_KW_AND] = parse_and,
		[IVY_KW_OR] = parse_or,
		[IVY_KW_NOT] = parse_not,
	},
};