// This file defines how to compile indexing like `list[i]` or `ptr[]`

#include <stdbool.h>

#include "../ast.h"
#include "../config.h"
#include "../environment.h"
#include "../stdlib/text.h"
#include "../stdlib/util.h"
#include "../typecheck.h"
#include "compilation.h"

public
Text_t compile_indexing(env_t *env, ast_t *ast, bool checked) {
    DeclareMatch(indexing, ast, Index);
    type_t *indexed_type = get_type(env, indexing->indexed);
    if (!indexing->index) {
        if (indexed_type->tag != PointerType)
            code_err(ast, "Only pointers can use the '[]' operator to "
                          "dereference "
                          "the entire value.");
        DeclareMatch(ptr, indexed_type, PointerType);
        if (ptr->pointed->tag == ListType) {
            return Texts("*({ List_t *list = ", compile(env, indexing->indexed), "; LIST_INCREF(*list); list; })");
        } else if (ptr->pointed->tag == TableType) {
            return Texts("*({ Table_t *t = ", compile(env, indexing->indexed), "; TABLE_INCREF(*t); t; })");
        } else {
            return Texts("*(", compile(env, indexing->indexed), ")");
        }
    }

    type_t *container_t = value_type(indexed_type);
    type_t *index_t = get_type(env, indexing->index);
    if (container_t->tag == ListType) {
        if (index_t->tag != IntType && index_t->tag != BigIntType && index_t->tag != ByteType)
            code_err(indexing->index, "Lists can only be indexed by integers, not ", type_to_text(index_t));
        type_t *item_type = Match(container_t, ListType)->item_type;
        Text_t list = compile_to_pointer_depth(env, indexing->indexed, 0, false);
        Text_t index_code =
            indexing->index->tag == Int
                ? compile_int_to_type(env, indexing->index, Type(IntType, .bits = TYPE_IBITS64))
                : (index_t->tag == BigIntType ? Texts("Int64$from_int(", compile(env, indexing->index), ", no)")
                                              : Texts("(Int64_t)(", compile(env, indexing->index), ")"));
        if (checked) {
            int64_t start = (int64_t)(ast->start - ast->file->text), end = (int64_t)(ast->end - ast->file->text);
            Text_t code = Texts("List_get_checked(", list, ", ", index_code, ", ", compile_type(item_type), ", ", start,
                                ", ", end, ")");
            if (item_type->tag == OptionalType) {
                int64_t line = get_line_number(ast->file, ast->start);
                return Texts("({ ", compile_declaration(item_type, Text("opt")), " = ", code, "; ", "if unlikely (",
                             check_none(item_type, Text("opt")), ")\n", "#line ", line, "\n", "fail_source(",
                             quoted_str(ast->file->filename), ", ", start, ", ", end, ", ",
                             "\"This was expected to be a value, but it's `none`\\n\");\n",
                             optional_into_nonnone(item_type, Text("opt")), "; })");
            }
            return code;
        } else if (item_type->tag == OptionalType) {
            return Texts("List_get(", list, ", ", index_code, ", ", compile_type(item_type), ", value, value,",
                         compile_none(item_type), ")");
        } else {
            return Texts("List_get(", list, ", ", index_code, ", ", compile_type(item_type), ", value, ",
                         promote_to_optional(item_type, Text("value")), ", ", compile_none(item_type), ")");
        }
    } else if (container_t->tag == TableType) {
        DeclareMatch(table_type, container_t, TableType);
        if (table_type->default_value) {
            return Texts("Table$get_or_default(", compile_to_pointer_depth(env, indexing->indexed, 0, false), ", ",
                         compile_type(table_type->key_type), ", ", compile_type(table_type->value_type), ", ",
                         compile_to_type(env, indexing->index, table_type->key_type), ", ",
                         compile_to_type(env, table_type->default_value, table_type->value_type), ", ",
                         compile_type_info(container_t), ")");
        } else if (checked) {
            int64_t start = (int64_t)(ast->start - ast->file->text), end = (int64_t)(ast->end - ast->file->text);
            return Texts("Table$get_checked(", compile_to_pointer_depth(env, indexing->indexed, 0, false), ", ",
                         compile_type(table_type->key_type), ", ", compile_type(table_type->value_type), ", ",
                         compile(env, indexing->index), ", ", start, ", ", end, ", ", compile_type_info(container_t),
                         ")");
        } else {
            return Texts("Table$get_optional(", compile_to_pointer_depth(env, indexing->indexed, 0, false), ", ",
                         compile_type(table_type->key_type), ", ", compile_type(table_type->value_type), ", ",
                         compile_to_type(env, indexing->index, table_type->key_type),
                         ", "
                         "_, ",
                         promote_to_optional(table_type->value_type, Text("(*_)")), ", ",
                         compile_none(table_type->value_type), ", ", compile_type_info(container_t), ")");
        }
    } else if (container_t->tag == TextType) {
        if (checked) {
            int64_t start = (int64_t)(ast->start - ast->file->text), end = (int64_t)(ast->end - ast->file->text);
            return Texts("Text$cluster_checked(", compile_to_pointer_depth(env, indexing->indexed, 0, false), ", ",
                         compile_to_type(env, indexing->index, Type(BigIntType)), ", ", start, ", ", end, ")");
        } else {
            return Texts("Text$cluster(", compile_to_pointer_depth(env, indexing->indexed, 0, false), ", ",
                         compile_to_type(env, indexing->index, Type(BigIntType)), ")");
        }
    } else {
        code_err(ast, "Indexing is not supported for type: ", type_to_text(container_t));
    }
}