/*
 * This file is part of the MicroPython project, http://micropython.org/
 *
 * The MIT License (MIT)
 *
 * Copyright (c) 2013-2019 Damien P. George
 * Copyright (c) 2014 Paul Sokolovsky
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in
 * all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
 * THE SOFTWARE.
 */

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

#include "py/compile.h"
#include "py/objmodule.h"
#include "py/persistentcode.h"
#include "py/runtime.h"
#include "py/builtin.h"
#include "py/frozenmod.h"

#if MICROPY_DEBUG_VERBOSE // print debugging info
#define DEBUG_PRINT (1)
#define DEBUG_printf DEBUG_printf
#else // don't print debugging info
#define DEBUG_PRINT (0)
#define DEBUG_printf(...) (void)0
#endif

#if MICROPY_ENABLE_EXTERNAL_IMPORT

#define PATH_SEP_CHAR '/'

#define printf(...) ((void)0)

bool mp_obj_is_package(mp_obj_t module) {
 mp_obj_t dest[2];
 mp_load_method_maybe(module, MP_QSTR___path__, dest);
 return dest[0] != MP_OBJ_NULL;
}

// Stat either frozen or normal module by a given path
// (whatever is available, if at all).
STATIC mp_import_stat_t mp_import_stat_any(const char *path) {
 #if MICROPY_MODULE_FROZEN
 mp_import_stat_t st = mp_frozen_stat(path);
 if (st != MP_IMPORT_STAT_NO_EXIST) {
 return st;
 }
 #endif
 
 return mp_import_stat(path);
}

STATIC mp_import_stat_t stat_file_py_or_mpy(vstr_t *path) {
 mp_import_stat_t stat = mp_import_stat_any(vstr_null_terminated_str(path));
 if (stat == MP_IMPORT_STAT_FILE) {
 return stat;
 }

 #if MICROPY_PERSISTENT_CODE_LOAD
 vstr_ins_byte(path, path->len - 2, 'm');
 stat = mp_import_stat_any(vstr_null_terminated_str(path));
 if (stat == MP_IMPORT_STAT_FILE) {
 return stat;
 }
 #endif

 return MP_IMPORT_STAT_NO_EXIST;
}

STATIC mp_import_stat_t stat_dir_or_file(vstr_t *path) {
 mp_import_stat_t stat = mp_import_stat_any(vstr_null_terminated_str(path));
 DEBUG_printf("stat %s: %d\n", vstr_str(path), stat);
 if (stat == MP_IMPORT_STAT_DIR) {
 return stat;
 }

 // not a directory, add .py and try as a file
 vstr_add_str(path, ".py");
 return stat_file_py_or_mpy(path);
}

STATIC mp_import_stat_t find_file(const char *file_str, uint file_len, vstr_t *dest) {
 #if MICROPY_PY_SYS
 // extract the list of paths
 size_t path_num;
 mp_obj_t *path_items;
 mp_obj_list_get(mp_sys_path, &path_num, &path_items);
 printf("Delphi: %s : %d : path_num = %u\n", __FUNCTION__, __LINE__, path_num);
 if (path_num != 0) {
 // go through each path looking for a directory or file
 for (size_t i = 0; i < path_num; i++) {
 vstr_reset(dest);
 size_t p_len;
 const char *p = mp_obj_str_get_data(path_items[i], &p_len);
 if (p_len > 0) {
 vstr_add_strn(dest, p, p_len);
 vstr_add_char(dest, PATH_SEP_CHAR);
 }
 vstr_add_strn(dest, file_str, file_len);
 printf("Delphi: %s : %d : dest = %s\n", __FUNCTION__, __LINE__, vstr_null_terminated_str(dest));
 mp_import_stat_t stat = stat_dir_or_file(dest);
 if (stat != MP_IMPORT_STAT_NO_EXIST) {
 return stat;
 }
 }

 // could not find a directory or file
 return MP_IMPORT_STAT_NO_EXIST;
 }
 #endif

 // mp_sys_path is empty, so just use the given file name
 vstr_add_strn(dest, file_str, file_len);
 return stat_dir_or_file(dest);
}

#if MICROPY_MODULE_FROZEN_STR || MICROPY_ENABLE_COMPILER
STATIC void do_load_from_lexer(mp_obj_t module_obj, mp_lexer_t *lex) {
 #if MICROPY_PY___FILE__
 qstr source_name = lex->source_name;
 mp_store_attr(module_obj, MP_QSTR___file__, MP_OBJ_NEW_QSTR(source_name));
 #endif

 // parse, compile and execute the module in its context
 mp_obj_dict_t *mod_globals = mp_obj_module_get_globals(module_obj);
 mp_parse_compile_execute(lex, MP_PARSE_FILE_INPUT, mod_globals, mod_globals);
}
#endif

#if MICROPY_PERSISTENT_CODE_LOAD || MICROPY_MODULE_FROZEN_MPY
STATIC void do_execute_raw_code(mp_obj_t module_obj, mp_raw_code_t *raw_code, const char *source_name) {
 (void)source_name;

 #if MICROPY_PY___FILE__
 mp_store_attr(module_obj, MP_QSTR___file__, MP_OBJ_NEW_QSTR(qstr_from_str(source_name)));
 #endif

 // execute the module in its context
 mp_obj_dict_t *mod_globals = mp_obj_module_get_globals(module_obj);

 // save context
 mp_obj_dict_t *volatile old_globals = mp_globals_get();
 mp_obj_dict_t *volatile old_locals = mp_locals_get();

 // set new context
 mp_globals_set(mod_globals);
 mp_locals_set(mod_globals);

 nlr_buf_t nlr;
 if (nlr_push(&nlr) == 0) {
 mp_obj_t module_fun = mp_make_function_from_raw_code(raw_code, MP_OBJ_NULL, MP_OBJ_NULL);
 mp_call_function_0(module_fun);

 // finish nlr block, restore context
 nlr_pop();
 mp_globals_set(old_globals);
 mp_locals_set(old_locals);
 } else {
 // exception; restore context and re-raise same exception
 mp_globals_set(old_globals);
 mp_locals_set(old_locals);
 nlr_jump(nlr.ret_val);
 }
}
#endif

STATIC void do_load(mp_obj_t module_obj, vstr_t *file) {
 #if MICROPY_MODULE_FROZEN || MICROPY_ENABLE_COMPILER || (MICROPY_PERSISTENT_CODE_LOAD && MICROPY_HAS_FILE_READER)
 char *file_str = vstr_null_terminated_str(file);
 #endif
 printf("Delphi: %s : %d : file_str = %s\n", __FUNCTION__, __LINE__, file_str);
 // If we support frozen modules (either as str or mpy) then try to find the
 // requested filename in the list of frozen module filenames.
 #if MICROPY_MODULE_FROZEN
 void *modref;
 int frozen_type = mp_find_frozen_module(file_str, file->len, &modref);
 #endif

 // If we support frozen str modules and the compiler is enabled, and we
 // found the filename in the list of frozen files, then load and execute it.
 #if MICROPY_MODULE_FROZEN_STR
 if (frozen_type == MP_FROZEN_STR) {
 do_load_from_lexer(module_obj, modref);
 return;
 }
 #endif

 // If we support frozen mpy modules and we found a corresponding file (and
 // its data) in the list of frozen files, execute it.
 #if MICROPY_MODULE_FROZEN_MPY
 if (frozen_type == MP_FROZEN_MPY) {
 do_execute_raw_code(module_obj, modref, file_str);
 return;
 }
 #endif

 // If we support loading .mpy files then check if the file extension is of
 // the correct format and, if so, load and execute the file.
 #if MICROPY_HAS_FILE_READER && MICROPY_PERSISTENT_CODE_LOAD
 if (file_str[file->len - 3] == 'm') {
 mp_raw_code_t *raw_code = mp_raw_code_load_file(file_str);
 do_execute_raw_code(module_obj, raw_code, file_str);
 return;
 }
 #endif

 // If we can compile scripts then load the file and compile and execute it.
 #if MICROPY_ENABLE_COMPILER
 {
 mp_lexer_t *lex = mp_lexer_new_from_file(file_str);
 do_load_from_lexer(module_obj, lex);
 return;
 }
 #else
 // If we get here then the file was not frozen and we can't compile scripts.
 mp_raise_msg(&mp_type_ImportError, MP_ERROR_TEXT("script compilation not supported"));
 #endif
}

STATIC void chop_component(const char *start, const char **end) {
 const char *p = *end;
 while (p > start) {
 if (*--p == '.') {
 *end = p;
 return;
 }
 }
 *end = p;
}

mp_obj_t mp_builtin___import__(size_t n_args, const mp_obj_t *args) {
 #if DEBUG_PRINT
 DEBUG_printf("__import__:\n");
 for (size_t i = 0; i < n_args; i++) {
 DEBUG_printf(" ");
 mp_obj_print(args[i], PRINT_REPR);
 DEBUG_printf("\n");
 }
 #endif

 mp_obj_t module_name = args[0];
 mp_obj_t fromtuple = mp_const_none;
 mp_int_t level = 0;
 if (n_args >= 4) {
 fromtuple = args[3];
 if (n_args >= 5) {
 level = MP_OBJ_SMALL_INT_VALUE(args[4]);
 if (level < 0) {
 mp_raise_ValueError(NULL);
 }
 }
 }

 size_t mod_len;
 const char *mod_str = mp_obj_str_get_data(module_name, &mod_len);

 if (level != 0) {
 // What we want to do here is to take name of current module,
 // chop <level> trailing components, and concatenate with passed-in
 // module name, thus resolving relative import name into absolute.
 // This even appears to be correct per
 // http://legacy.python.org/dev/peps/pep-0328/#relative-imports-and-name
 // "Relative imports use a module's __name__ attribute to determine that
 // module's position in the package hierarchy."
 level--;
 mp_obj_t this_name_q = mp_obj_dict_get(MP_OBJ_FROM_PTR(mp_globals_get()), MP_OBJ_NEW_QSTR(MP_QSTR___name__));
 assert(this_name_q != MP_OBJ_NULL);
 #if MICROPY_CPYTHON_COMPAT
 if (MP_OBJ_QSTR_VALUE(this_name_q) == MP_QSTR___main__) {
 // This is a module run by -m command-line switch, get its real name from backup attribute
 this_name_q = mp_obj_dict_get(MP_OBJ_FROM_PTR(mp_globals_get()), MP_OBJ_NEW_QSTR(MP_QSTR___main__));
 }
 #endif
 mp_map_t *globals_map = &mp_globals_get()->map;
 mp_map_elem_t *elem = mp_map_lookup(globals_map, MP_OBJ_NEW_QSTR(MP_QSTR___path__), MP_MAP_LOOKUP);
 bool is_pkg = (elem != NULL);

 #if DEBUG_PRINT
 DEBUG_printf("Current module/package: ");
 mp_obj_print(this_name_q, PRINT_REPR);
 DEBUG_printf(", is_package: %d", is_pkg);
 DEBUG_printf("\n");
 #endif
 
 printf("Current module/package: ");
 mp_obj_print(this_name_q, PRINT_REPR);
 printf(", is_package: %d", is_pkg);
 printf("\n");

 size_t this_name_l;
 const char *this_name = mp_obj_str_get_data(this_name_q, &this_name_l);

 const char *p = this_name + this_name_l;
 if (!is_pkg) {
 // We have module, but relative imports are anchored at package, so
 // go there.
 chop_component(this_name, &p);
 }

 while (level--) {
 chop_component(this_name, &p);
 }

 // We must have some component left over to import from
 if (p == this_name) {
 mp_raise_ValueError(MP_ERROR_TEXT("can't perform relative import"));
 }

 uint new_mod_l = (mod_len == 0 ? (size_t)(p - this_name) : (size_t)(p - this_name) + 1 + mod_len);
 char *new_mod = mp_local_alloc(new_mod_l);
 memcpy(new_mod, this_name, p - this_name);
 if (mod_len != 0) {
 new_mod[p - this_name] = '.';
 memcpy(new_mod + (p - this_name) + 1, mod_str, mod_len);
 }

 qstr new_mod_q = qstr_from_strn(new_mod, new_mod_l);
 mp_local_free(new_mod);
 printf("Resolved base name for relative import: '%s'\n", qstr_str(new_mod_q));
 module_name = MP_OBJ_NEW_QSTR(new_mod_q);
 mod_str = qstr_str(new_mod_q);
 mod_len = new_mod_l;
 }

 if (mod_len == 0) {
 mp_raise_ValueError(NULL);
 }

 // check if module already exists
 qstr module_name_qstr = mp_obj_str_get_qstr(module_name);
 mp_obj_t module_obj = mp_module_get(module_name_qstr);
 if (module_obj != MP_OBJ_NULL) {
 DEBUG_printf("Module already loaded\n");
 // If it's not a package, return module right away
 char *p = strchr(mod_str, '.');
 if (p == NULL) {
 return module_obj;
 }
 // If fromlist is not empty, return leaf module
 if (fromtuple != mp_const_none) {
 return module_obj;
 }
 // Otherwise, we need to return top-level package
 qstr pkg_name = qstr_from_strn(mod_str, p - mod_str);
 return mp_module_get(pkg_name);
 }
 printf("Module not yet loaded\n");

 uint last = 0;
 VSTR_FIXED(path, MICROPY_ALLOC_PATH_MAX)
 module_obj = MP_OBJ_NULL;
 mp_obj_t top_module_obj = MP_OBJ_NULL;
 mp_obj_t outer_module_obj = MP_OBJ_NULL;
 uint i;
 for (i = 1; i <= mod_len; i++) {
 if (i == mod_len || mod_str[i] == '.') {
 // create a qstr for the module name up to this depth
 qstr mod_name = qstr_from_strn(mod_str, i);
 printf("Processing module: %s\n", qstr_str(mod_name));
 printf("Previous path: =%u.%s=\n", vstr_len(&path), vstr_str(&path));

 // find the file corresponding to the module name
 mp_import_stat_t stat;
 if (vstr_len(&path) == 0) {
 // first module in the dotted-name; search for a directory or file
 stat = find_file(mod_str, i, &path);
 printf("Delphi: %s : %d : stat = %d\n", __FUNCTION__, __LINE__, stat);
 } else {
 // latter module in the dotted-name; append to path
 vstr_add_char(&path, PATH_SEP_CHAR);
 vstr_add_strn(&path, mod_str + last, i - last);
 stat = stat_dir_or_file(&path);
 }
 printf("Current path: %u.%s\n", vstr_len(&path), vstr_str(&path));

 if (stat == MP_IMPORT_STAT_NO_EXIST) {
 module_obj = MP_OBJ_NULL;
 #if MICROPY_MODULE_WEAK_LINKS
 // check if there is a weak link to this module
 if (i == mod_len) {
 module_obj = mp_module_search_umodule(mod_str);
 if (module_obj != MP_OBJ_NULL) {
 // found weak linked module
 mp_module_call_init(mod_name, module_obj);
 }
 }
 #endif
 if (module_obj == MP_OBJ_NULL) {
 // couldn't find the file, so fail
 #if MICROPY_ERROR_REPORTING == MICROPY_ERROR_REPORTING_TERSE
 mp_raise_msg(&mp_type_ImportError, MP_ERROR_TEXT("module not found"));
 #else
 mp_raise_msg_varg(&mp_type_ImportError, MP_ERROR_TEXT("no module named '%q'"), mod_name);
 #endif
 }
 } else {
 // found the file, so get the module
 module_obj = mp_module_get(mod_name);
 }

 if (module_obj == MP_OBJ_NULL) {
 // module not already loaded, so load it!

 module_obj = mp_obj_new_module(mod_name);

 // if args[3] (fromtuple) has magic value False, set up
 // this module for command-line "-m" option (set module's
 // name to __main__ instead of real name). Do this only
 // for *modules* however - packages never have their names
 // replaced, instead they're -m'ed using a special __main__
 // submodule in them. (This all apparently is done to not
 // touch package name itself, which is important for future
 // imports).
 if (i == mod_len && fromtuple == mp_const_false && stat != MP_IMPORT_STAT_DIR) {
 mp_obj_module_t *o = MP_OBJ_TO_PTR(module_obj);
 mp_obj_dict_store(MP_OBJ_FROM_PTR(o->globals), MP_OBJ_NEW_QSTR(MP_QSTR___name__), MP_OBJ_NEW_QSTR(MP_QSTR___main__));
 #if MICROPY_CPYTHON_COMPAT
 // Store module as "__main__" in the dictionary of loaded modules (returned by sys.modules).
 mp_obj_dict_store(MP_OBJ_FROM_PTR(&MP_STATE_VM(mp_loaded_modules_dict)), MP_OBJ_NEW_QSTR(MP_QSTR___main__), module_obj);
 // Store real name in "__main__" attribute. Chosen semi-randonly, to reuse existing qstr's.
 mp_obj_dict_store(MP_OBJ_FROM_PTR(o->globals), MP_OBJ_NEW_QSTR(MP_QSTR___main__), MP_OBJ_NEW_QSTR(mod_name));
 #endif
 }

 if (stat == MP_IMPORT_STAT_DIR) {
 printf("%u.*%s is dir\n", vstr_len(&path), vstr_str(&path));
 // https://docs.python.org/3/reference/import.html
 // "Specifically, any module that contains a __path__ attribute is considered a package."
 mp_store_attr(module_obj, MP_QSTR___path__, mp_obj_new_str(vstr_str(&path), vstr_len(&path)));
 size_t orig_path_len = path.len;
 vstr_add_char(&path, PATH_SEP_CHAR);
 vstr_add_str(&path, "__init__.py");
 if (stat_file_py_or_mpy(&path) != MP_IMPORT_STAT_FILE) {
 // mp_warning("%s is imported as namespace package", vstr_str(&path));
 } else {
 do_load(module_obj, &path);
 }
 path.len = orig_path_len;
 } else { // MP_IMPORT_STAT_FILE
 printf("Delphi: %s : %d : path = %s\n", __FUNCTION__, __LINE__, vstr_str(&path));
 do_load(module_obj, &path);
 // This should be the last component in the import path. If there are
 // remaining components then it's an ImportError because the current path
 // (the module that was just loaded) is not a package. This will be caught
 // on the next iteration because the file will not exist.
 }
 }
 if (outer_module_obj != MP_OBJ_NULL) {
 qstr s = qstr_from_strn(mod_str + last, i - last);
 mp_store_attr(outer_module_obj, s, module_obj);
 }
 outer_module_obj = module_obj;
 if (top_module_obj == MP_OBJ_NULL) {
 top_module_obj = module_obj;
 }
 last = i + 1;
 }
 }

 // If fromlist is not empty, return leaf module
 if (fromtuple != mp_const_none) {
 return module_obj;
 }
 // Otherwise, we need to return top-level package
 return top_module_obj;
}

#else // MICROPY_ENABLE_EXTERNAL_IMPORT

mp_obj_t mp_builtin___import__(size_t n_args, const mp_obj_t *args) {
 // Check that it's not a relative import
 if (n_args >= 5 && MP_OBJ_SMALL_INT_VALUE(args[4]) != 0) {
 mp_raise_NotImplementedError(MP_ERROR_TEXT("relative import"));
 }

 // Check if module already exists, and return it if it does
 qstr module_name_qstr = mp_obj_str_get_qstr(args[0]);
 mp_obj_t module_obj = mp_module_get(module_name_qstr);
 if (module_obj != MP_OBJ_NULL) {
 return module_obj;
 }

 #if MICROPY_MODULE_WEAK_LINKS
 // Check if there is a weak link to this module
 module_obj = mp_module_search_umodule(qstr_str(module_name_qstr));
 if (module_obj != MP_OBJ_NULL) {
 // Found weak-linked module
 mp_module_call_init(module_name_qstr, module_obj);
 return module_obj;
 }
 #endif

 // Couldn't find the module, so fail
 #if MICROPY_ERROR_REPORTING == MICROPY_ERROR_REPORTING_TERSE
 mp_raise_msg(&mp_type_ImportError, MP_ERROR_TEXT("module not found"));
 #else
 mp_raise_msg_varg(&mp_type_ImportError, MP_ERROR_TEXT("no module named '%q'"), module_name_qstr);
 #endif
}

#endif // MICROPY_ENABLE_EXTERNAL_IMPORT

MP_DEFINE_CONST_FUN_OBJ_VAR_BETWEEN(mp_builtin___import___obj, 1, 5, mp_builtin___import__);