#include <assert.h>
#include <bshell/ast.h>
#include <bshell/status.h>
#include <stdlib.h>
#include <string.h>

extern struct bshell_ast_node_definition null_bshell_ast_node;
extern struct bshell_ast_node_definition int_bshell_ast_node;
extern struct bshell_ast_node_definition double_bshell_ast_node;
extern struct bshell_ast_node_definition word_bshell_ast_node;
extern struct bshell_ast_node_definition var_bshell_ast_node;
extern struct bshell_ast_node_definition string_bshell_ast_node;
extern struct bshell_ast_node_definition fstring_bshell_ast_node;
extern struct bshell_ast_node_definition cmdcall_bshell_ast_node;
extern struct bshell_ast_node_definition pipeline_bshell_ast_node;
extern struct bshell_ast_node_definition redirection_bshell_ast_node;
extern struct bshell_ast_node_definition block_bshell_ast_node;
extern struct bshell_ast_node_definition stmt_list_bshell_ast_node;
extern struct bshell_ast_node_definition func_bshell_ast_node;
extern struct bshell_ast_node_definition array_bshell_ast_node;
extern struct bshell_ast_node_definition hashtable_bshell_ast_node;
extern struct bshell_ast_node_definition hashtable_item_bshell_ast_node;
extern struct bshell_ast_node_definition if_bshell_ast_node;
extern struct bshell_ast_node_definition if_branch_bshell_ast_node;
extern struct bshell_ast_node_definition op_bshell_ast_node;

static const struct bshell_ast_node_definition *bshell_ast_node_definitions[]
	= {
		[BSHELL_AST_NULL] = &null_bshell_ast_node,
		[BSHELL_AST_INT] = &int_bshell_ast_node,
		[BSHELL_AST_DOUBLE] = &double_bshell_ast_node,
		[BSHELL_AST_WORD] = &word_bshell_ast_node,
		[BSHELL_AST_VAR] = &var_bshell_ast_node,
		[BSHELL_AST_STRING] = &string_bshell_ast_node,
		[BSHELL_AST_FSTRING] = &fstring_bshell_ast_node,
		[BSHELL_AST_CMDCALL] = &cmdcall_bshell_ast_node,
		[BSHELL_AST_PIPELINE] = &pipeline_bshell_ast_node,
		[BSHELL_AST_REDIRECTION] = &redirection_bshell_ast_node,
		[BSHELL_AST_BLOCK] = &block_bshell_ast_node,
		[BSHELL_AST_STMT_LIST] = &stmt_list_bshell_ast_node,
		[BSHELL_AST_FUNC] = &func_bshell_ast_node,
		[BSHELL_AST_ARRAY] = &array_bshell_ast_node,
		[BSHELL_AST_IF] = &if_bshell_ast_node,
		[BSHELL_AST_IF_BRANCH] = &if_branch_bshell_ast_node,
		[BSHELL_AST_HASHTABLE] = &hashtable_bshell_ast_node,
		[BSHELL_AST_HASHTABLE_ITEM] = &hashtable_item_bshell_ast_node,
		[BSHELL_AST_OP] = &op_bshell_ast_node,
};
static const size_t nr_bshell_ast_node_definitions
	= sizeof bshell_ast_node_definitions
        / sizeof bshell_ast_node_definitions[0];

struct bshell_ast_node *bshell_ast_node_create(enum bshell_ast_node_type type)
{
	assert(type < nr_bshell_ast_node_definitions);

	const struct bshell_ast_node_definition *def
		= bshell_ast_node_definitions[type];
	struct bshell_ast_node *out = malloc(def->def_node_size);
	if (!out) {
		return NULL;
	}

	memset(out, 0x0, def->def_node_size);

	out->n_type = type;

	return out;
}

void bshell_ast_node_destroy(struct bshell_ast_node *node)
{
	assert(node->n_type < nr_bshell_ast_node_definitions);

	struct bshell_ast_iterator it = {0};
	bshell_ast_iterator_enqueue(&it, node);

	while (1) {
		node = bshell_ast_iterator_peek(&it);
		if (!node) {
			break;
		}

		const struct bshell_ast_node_definition *def
			= bshell_ast_node_definitions[node->n_type];

		if (def->def_cleanup) {
			def->def_cleanup(node);
		}

		bshell_ast_iterator_dequeue(&it);
		free(node);
	}
}

void bshell_ast_node_to_string(const struct bshell_ast_node *node, fx_bstr *out)
{
	const struct bshell_ast_node_definition *def
		= bshell_ast_node_definitions[node->n_type];
	if (def->def_to_string) {
		def->def_to_string(node, out);
	}
}

#define ENUM_STR(x)                                                            \
	case x:                                                                \
		return #x

const char *bshell_ast_node_type_to_string(enum bshell_ast_node_type type)
{
	switch (type) {
		ENUM_STR(BSHELL_AST_NONE);
		ENUM_STR(BSHELL_AST_NULL);
		ENUM_STR(BSHELL_AST_STMT_LIST);
		ENUM_STR(BSHELL_AST_INT);
		ENUM_STR(BSHELL_AST_DOUBLE);
		ENUM_STR(BSHELL_AST_WORD);
		ENUM_STR(BSHELL_AST_STRING);
		ENUM_STR(BSHELL_AST_FSTRING);
		ENUM_STR(BSHELL_AST_VAR);
		ENUM_STR(BSHELL_AST_VAR_SPLAT);
		ENUM_STR(BSHELL_AST_FLAG);
		ENUM_STR(BSHELL_AST_CMDCALL);
		ENUM_STR(BSHELL_AST_PIPELINE);
		ENUM_STR(BSHELL_AST_REDIRECTION);
		ENUM_STR(BSHELL_AST_BLOCK);
		ENUM_STR(BSHELL_AST_FUNC);
		ENUM_STR(BSHELL_AST_IF);
		ENUM_STR(BSHELL_AST_IF_BRANCH);
		ENUM_STR(BSHELL_AST_OP);
		ENUM_STR(BSHELL_AST_ARRAY);
		ENUM_STR(BSHELL_AST_HASHTABLE);
		ENUM_STR(BSHELL_AST_HASHTABLE_ITEM);
	default:
		return "<unknown>";
	}
}

struct bshell_ast_node *bshell_ast_iterator_peek(struct bshell_ast_iterator *it)
{
	fx_queue_entry *cur = fx_queue_first(&it->it_queue);
	if (!cur) {
		return NULL;
	}

	return fx_unbox(struct bshell_ast_node, cur, n_it.e_entry);
}

struct bshell_ast_node *bshell_ast_iterator_dequeue(
	struct bshell_ast_iterator *it)
{
	fx_queue_entry *cur = fx_queue_first(&it->it_queue);
	if (!cur) {
		return NULL;
	}

	struct bshell_ast_node *node = fx_unbox(
		struct bshell_ast_node,
		cur,
		n_it.e_entry);
	const struct bshell_ast_node_definition *def
		= bshell_ast_node_definitions[node->n_type];

	it->it_insert_after = cur;
	if (def->def_collect_children) {
		def->def_collect_children(node, it);
	}

	fx_queue_pop_front(&it->it_queue);
	return fx_unbox(struct bshell_ast_node, cur, n_it.e_entry);
}

void bshell_ast_iterator_enqueue(
	struct bshell_ast_iterator *it,
	struct bshell_ast_node *node)
{
	unsigned long new_depth = 0;

	fx_queue_entry *cur = fx_queue_first(&it->it_queue);
	if (cur) {
		struct bshell_ast_node *cur_node = fx_unbox(
			struct bshell_ast_node,
			cur,
			n_it.e_entry);
		new_depth = cur_node->n_it.e_depth + 1;
	}

	node->n_it.e_depth = new_depth;

	if (!it->it_insert_after) {
		fx_queue_push_back(&it->it_queue, &node->n_it.e_entry);
		return;
	}

	fx_queue_insert_after(
		&it->it_queue,
		&node->n_it.e_entry,
		it->it_insert_after);
	it->it_insert_after = &node->n_it.e_entry;
}

enum bshell_status bshell_ast_node_iterate(
	struct bshell_ast_node *node,
	struct bshell_ast_iterator *it,
	bshell_ast_iterator_callback callback,
	void *arg)
{
	fx_queue_push_back(&it->it_queue, &node->n_it.e_entry);
	node->n_it.e_depth = 0;

	fx_queue_entry *entry = fx_queue_first(&it->it_queue);

	while (entry) {
		struct bshell_ast_iterator_entry *it_entry = fx_unbox(
			struct bshell_ast_iterator_entry,
			entry,
			e_entry);
		node = fx_unbox(struct bshell_ast_node, it_entry, n_it);

		if (!node) {
			/* this should never happen. */
			return BSHELL_ERR_INTERNAL_FAILURE;
		}

		struct bshell_ast_iterate_result result = callback(
			node,
			BSHELL_AST_ITERATION_PRE,
			it,
			arg);
		if (result.r_status != BSHELL_SUCCESS
		    || result.r_flags & BSHELL_AST_ITERATE_STOP) {
			return result.r_status;
		}

		const struct bshell_ast_node_definition *type
			= bshell_ast_node_definitions[node->n_type];
		if (type->def_collect_children
		    && result.r_flags & BSHELL_AST_ITERATE_ADD_CHILDREN) {
			it->it_insert_after = entry;
			type->def_collect_children(node, it);
		}

		if (!(result.r_flags & BSHELL_AST_ITERATE_REPEAT)) {
			entry = fx_queue_next(entry);
		}
	}

	while (!fx_queue_empty(&it->it_queue)) {
		fx_queue_entry *entry = fx_queue_last(&it->it_queue);
		if (!entry) {
			break;
		}

		node = fx_unbox(struct bshell_ast_node, entry, n_it);

		if (!node) {
			/* this should never happen. */
			return BSHELL_ERR_INTERNAL_FAILURE;
		}

		struct bshell_ast_iterate_result result = callback(
			node,
			BSHELL_AST_ITERATION_POST,
			it,
			arg);
		if (result.r_status != BSHELL_SUCCESS
		    || result.r_flags & BSHELL_AST_ITERATE_STOP) {
			return result.r_status;
		}

		if (!(result.r_flags & BSHELL_AST_ITERATE_REPEAT)) {
			fx_queue_pop_back(&it->it_queue);
		}
	}

	return BSHELL_SUCCESS;
}