#include "block.h"
#include "ctx.h"
#include "expr/expr.h"
#include "iterate.h"
#include "node.h"

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

enum package_type {
	PACKAGE_NONE = 0,
	/* package constructed using a list of key-value pairs. */
	PACKAGE_STATIC,
	/* package constructed using an (X for X in Y if Z) pattern. */
	PACKAGE_DYNAMIC,
};

struct package_parser_state {
	struct parser_state s_base;
	enum package_type s_type;

	struct ivy_ast_node *s_prev_node;
	unsigned int s_prev;

	/* only used for PACKAGE_STATIC */
	b_queue s_items;
	struct ivy_ast_node *s_next_index;
	unsigned int s_next_implicit_index;

	/* only used for PACKAGE_DYNAMIC */
	struct ivy_ast_node *s_transform;
	struct ivy_ast_node *s_item;
	struct ivy_ast_node *s_source;
	struct ivy_ast_node *s_cond;
};

static enum ivy_status add_package_item(struct package_parser_state *state, struct ivy_ast_node *index, struct ivy_ast_node *value)
{
	struct ivy_ast_pkg_static_item_node *item = (struct ivy_ast_pkg_static_item_node *)ast_node_create(IVY_AST_PKG_ITEM);
	if (!item) {
		return IVY_ERR_NO_MEMORY;
	}

	item->n_value = value;

	if (index) {
		item->n_index = index;
	} else {
		item->n_implicit_index = state->s_next_implicit_index++;
	}

	b_queue_push_back(&state->s_items, &item->n_base.n_entry);

	state->s_next_index = NULL;
	state->s_prev_node = NULL;

	return IVY_OK;
}

static struct ivy_ast_node *finalise_package(struct package_parser_state *state)
{
	struct ivy_ast_pkg_static_node *s = NULL;
	struct ivy_ast_pkg_dynamic_node *d = NULL;

	switch (state->s_type) {
	case PACKAGE_STATIC:
		s = (struct ivy_ast_pkg_static_node *)ast_node_create(IVY_AST_PKG_STATIC);

		if (!s) {
			return NULL;
		}

		s->n_items = state->s_items;
		state->s_items = B_QUEUE_INIT;
		return (struct ivy_ast_node *)s;
	case PACKAGE_DYNAMIC:
		d = (struct ivy_ast_pkg_dynamic_node *)ast_node_create(IVY_AST_PKG_DYNAMIC);
		if (!d) {
			return NULL;
		}

		d->n_transform = state->s_transform;
		d->n_item = state->s_item;
		d->n_source = state->s_source;
		d->n_cond = state->s_cond;

		state->s_transform = NULL;
		state->s_item = NULL;
		state->s_source = NULL;
		state->s_cond = NULL;

		return (struct ivy_ast_node *)d;
	default:
		return NULL;
	}
}

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

	if (state->s_type == PACKAGE_NONE) {
		state->s_type = PACKAGE_STATIC;
	}

	if (state->s_type != PACKAGE_STATIC) {
		/* this token cannot be used in this context. */
		return PARSE_RESULT(IVY_ERR_BAD_SYNTAX, 0);
	}

	if (state->s_prev != IVY_SYM_LEFT_BRACE && state->s_prev != IVY_SYM_COMMA) {
		/* token unexpected at this time. */
		return PARSE_RESULT(IVY_ERR_BAD_SYNTAX, 0);
	}

	if (!state->s_prev_node) {
		/* empty index expression. */
		return PARSE_RESULT(IVY_ERR_BAD_SYNTAX, 0);
	}

	state->s_prev = IVY_SYM_EQUAL_RIGHT_ANGLE;
	state->s_next_index = state->s_prev_node;
	state->s_prev_node = NULL;

	struct expr_parser_state *expr = (struct expr_parser_state *)parser_push_state(ctx, IVY_AST_EXPR, 0);
	expr_add_terminator(expr, IVY_SYM_COMMA);
	expr->s_subexpr_depth = 1;

	return PARSE_RESULT(IVY_OK, 0);
}

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

	if (state->s_type == PACKAGE_NONE) {
		state->s_type = PACKAGE_STATIC;
	}

	if (state->s_type != PACKAGE_STATIC) {
		/* this token cannot be used in this context. */
		return PARSE_RESULT(IVY_ERR_BAD_SYNTAX, 0);
	}

	if (state->s_prev != IVY_SYM_LEFT_BRACE && state->s_prev != IVY_SYM_COMMA && state->s_prev != IVY_SYM_EQUAL_RIGHT_ANGLE) {
		/* token unexpected at this time. */
		return PARSE_RESULT(IVY_ERR_BAD_SYNTAX, 0);
	}

	if (!state->s_prev_node) {
		/* empty value expression. */
		return PARSE_RESULT(IVY_ERR_BAD_SYNTAX, 0);
	}

	enum ivy_status status = add_package_item(state, state->s_next_index, state->s_prev_node);
	if (status != IVY_OK) {
		return PARSE_RESULT(status, 0);
	}

	state->s_prev = IVY_SYM_COMMA;

	struct expr_parser_state *expr = (struct expr_parser_state *)parser_push_state(ctx, IVY_AST_EXPR, 0);
	expr_add_terminator(expr, IVY_SYM_EQUAL_RIGHT_ANGLE);
	expr->s_subexpr_depth = 1;

	return PARSE_RESULT(IVY_OK, 0);
}

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

	if (state->s_type == PACKAGE_NONE) {
		state->s_type = PACKAGE_STATIC;
	}

	enum ivy_status status = IVY_OK;

	switch (state->s_type) {
	case PACKAGE_STATIC:
		if (state->s_prev != IVY_SYM_LEFT_BRACE && state->s_prev != IVY_SYM_COMMA && state->s_prev != IVY_SYM_EQUAL_RIGHT_ANGLE) {
			/* token unexpected at this time. */
			return PARSE_RESULT(IVY_ERR_BAD_SYNTAX, 0);
		}

		if (state->s_prev_node) {
			status = add_package_item(state, state->s_next_index, state->s_prev_node);
		}

		break;
	case PACKAGE_DYNAMIC:
		if (!state->s_prev_node) {
			/* empty expression */
			status = IVY_ERR_BAD_SYNTAX;
			break;
		}

		switch (state->s_prev) {
		case IVY_KW_IN:
			state->s_source = state->s_prev_node;
			break;
		case IVY_KW_IF:
			state->s_cond = state->s_prev_node;
			break;
		default:
			/* token unexpected at this time. */
			status = IVY_ERR_BAD_SYNTAX;
			break;
		}
		break;
	default:
		/* not sure how we got here. */
		status = IVY_ERR_INTERNAL_FAILURE;
		break;
	}

	if (status != IVY_OK) {
		return PARSE_RESULT(status, 0);
	}

	struct ivy_ast_node *pkg = finalise_package(state);
	if (!pkg) {
		return PARSE_RESULT(IVY_ERR_NO_MEMORY, 0);
	}

	parser_replace_current_node(ctx, pkg);
	parser_pop_state(ctx, STATE_ADD_NODE_TO_PARENT);

	return PARSE_RESULT(IVY_OK, 0);
}

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

	if (state->s_type == PACKAGE_NONE) {
		state->s_type = PACKAGE_DYNAMIC;
	}

	if (state->s_type != PACKAGE_DYNAMIC) {
		/* this token cannot be used in this context. */
		return PARSE_RESULT(IVY_ERR_BAD_SYNTAX, 0);
	}

	if (state->s_prev != IVY_SYM_LEFT_BRACE) {
		/* token unexpected at this time. */
		return PARSE_RESULT(IVY_ERR_BAD_SYNTAX, 0);
	}

	if (!state->s_prev_node) {
		/* empty expression. */
		return PARSE_RESULT(IVY_ERR_BAD_SYNTAX, 0);
	}

	state->s_prev = IVY_KW_FOR;
	state->s_transform = state->s_prev_node;
	state->s_prev_node = NULL;

	struct expr_parser_state *expr = (struct expr_parser_state *)parser_push_state(ctx, IVY_AST_EXPR, 0);
	expr_add_terminator(expr, IVY_KW_IN);
	expr->s_subexpr_depth = 1;

	return PARSE_RESULT(IVY_OK, 0);
}

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

	if (state->s_type != PACKAGE_DYNAMIC) {
		/* this token cannot be used in this context. */
		return PARSE_RESULT(IVY_ERR_BAD_SYNTAX, 0);
	}

	if (state->s_prev != IVY_KW_FOR) {
		/* token unexpected at this time. */
		return PARSE_RESULT(IVY_ERR_BAD_SYNTAX, 0);
	}

	if (!state->s_prev_node) {
		/* empty expression. */
		return PARSE_RESULT(IVY_ERR_BAD_SYNTAX, 0);
	}

	state->s_prev = IVY_KW_IN;
	state->s_item = state->s_prev_node;
	state->s_prev_node = NULL;

	struct expr_parser_state *expr = (struct expr_parser_state *)parser_push_state(ctx, IVY_AST_EXPR, 0);
	expr_add_terminator(expr, IVY_KW_IF);
	expr->s_subexpr_depth = 1;

	return PARSE_RESULT(IVY_OK, 0);
}

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

	if (state->s_type != PACKAGE_DYNAMIC) {
		/* this token cannot be used in this context. */
		return PARSE_RESULT(IVY_ERR_BAD_SYNTAX, 0);
	}

	if (state->s_prev != IVY_KW_IN) {
		/* token unexpected at this time. */
		return PARSE_RESULT(IVY_ERR_BAD_SYNTAX, 0);
	}

	if (!state->s_prev_node) {
		/* empty expression. */
		return PARSE_RESULT(IVY_ERR_BAD_SYNTAX, 0);
	}

	state->s_prev = IVY_KW_IF;
	state->s_source = state->s_prev_node;
	state->s_prev_node = NULL;

	struct expr_parser_state *expr = (struct expr_parser_state *)parser_push_state(ctx, IVY_AST_EXPR, 0);
	expr_add_terminator(expr, IVY_SYM_RIGHT_BRACE);
	expr->s_subexpr_depth = 1;

	return PARSE_RESULT(IVY_OK, 0);
}

static enum ivy_status add_child(
	struct parser_state *parent, struct ivy_ast_node *child)
{
	struct package_parser_state *state
		= (struct package_parser_state *)parent;

	if (state->s_prev_node) {
		return IVY_ERR_BAD_SYNTAX;
	}

	state->s_prev_node = child;
	return IVY_OK;
}

static void pkg_static_collect_children(
	struct ivy_ast_node *node, struct ivy_ast_node_iterator *iterator)
{
	struct ivy_ast_pkg_static_node *pkg = (struct ivy_ast_pkg_static_node *)node;
	
	b_queue_iterator it = {0};
	b_queue_foreach (&it, &pkg->n_items) {
		struct ivy_ast_node *item = b_unbox(struct ivy_ast_node, it.entry, n_entry);
		ast_node_iterator_enqueue_node(iterator, node, item);
	}
}


static void pkg_static_item_to_string(struct ivy_ast_node *node, b_string *str)
{
	struct ivy_ast_pkg_static_item_node *item = (struct ivy_ast_pkg_static_item_node *)node;

	b_string_append_cstr(str, ivy_ast_node_type_to_string(node->n_type));

	if (!item->n_index) {
		b_string_append_cstrf(str, " (%u)", item->n_implicit_index);
	}
}

static void pkg_static_item_collect_children(
	struct ivy_ast_node *node, struct ivy_ast_node_iterator *iterator)
{
	struct ivy_ast_pkg_static_item_node *item = (struct ivy_ast_pkg_static_item_node *)node;

	if (item->n_index) {
		ast_node_iterator_enqueue_node(iterator, node, item->n_index);
	}

	if (item->n_value) {
		ast_node_iterator_enqueue_node(iterator, node, item->n_value);
	}
}

static void pkg_dynamic_collect_children(
	struct ivy_ast_node *node, struct ivy_ast_node_iterator *iterator)
{
	struct ivy_ast_pkg_dynamic_node *pkg = (struct ivy_ast_pkg_dynamic_node *)node;

	if (pkg->n_transform) {
		ast_node_iterator_enqueue_node(iterator, node, pkg->n_transform);
	}

	if (pkg->n_item) {
		ast_node_iterator_enqueue_node(iterator, node, pkg->n_item);
	}

	if (pkg->n_source) {
		ast_node_iterator_enqueue_node(iterator, node, pkg->n_source);
	}

	if (pkg->n_cond) {
		ast_node_iterator_enqueue_node(iterator, node, pkg->n_cond);
	}
}

static void init_state(struct ivy_parser *ctx, struct parser_state *sp, uintptr_t arg)
{
	struct package_parser_state *state = (struct package_parser_state *)sp;
	state->s_type = PACKAGE_NONE;
	state->s_prev = IVY_SYM_LEFT_BRACE;
	state->s_next_implicit_index = 0;

	struct expr_parser_state *expr = (struct expr_parser_state *)parser_push_state(ctx, IVY_AST_EXPR, 0);
	expr_add_terminator(expr, IVY_KW_FOR);
	expr->s_subexpr_depth = 1;
}

struct ast_node_type pkg_node_ops = {
	.n_init_state = init_state,
	.n_add_child = add_child,
	.n_state_size = sizeof(struct package_parser_state),
	/* placeholder node, will be replaced with either ivy_ast_pkg_static_node
	 * or ivy_ast_pkg_dynamic_node when finished. */
	.n_node_size = sizeof(struct ivy_ast_node),
	.n_keyword_parsers = {
		KW_PARSER(FOR, parse_for),
		KW_PARSER(IN, parse_in),
		KW_PARSER(IF, parse_if),
	},
	.n_symbol_parsers = {
		SYM_PARSER(COMMA, parse_comma),
		SYM_PARSER(EQUAL_RIGHT_ANGLE, parse_equal_right_angle),
		SYM_PARSER(RIGHT_BRACE, parse_right_brace),
	},
};

struct ast_node_type pkg_static_node_ops = {
	.n_collect_children = pkg_static_collect_children,
	.n_state_size = sizeof(struct parser_state),
	.n_node_size = sizeof(struct ivy_ast_pkg_static_node),
};

struct ast_node_type pkg_static_item_node_ops = {
	.n_to_string = pkg_static_item_to_string,
	.n_collect_children = pkg_static_item_collect_children,
	.n_state_size = sizeof(struct parser_state),
	.n_node_size = sizeof(struct ivy_ast_pkg_static_item_node),
};

struct ast_node_type pkg_dynamic_node_ops = {
	.n_collect_children = pkg_dynamic_collect_children,
	.n_state_size = sizeof(struct parser_state),
	.n_node_size = sizeof(struct ivy_ast_pkg_dynamic_node),
};