/*
 * This file is part of the MicroPython project, http://micropython.org/
 *
 * The MIT License (MIT)
 *
 * Copyright (c) 2013-2021 Damien P. George and 2017, 2018 Rami Ali
 *
 * 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 <stdint.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>

#include "py/builtin.h"
#include "py/compile.h"
#include "py/runtime.h"
#include "py/repl.h"
#include "py/gc.h"
#include "py/mperrno.h"
#include "extmod/vfs.h"
#include "extmod/vfs_posix.h"
#include "shared/runtime/pyexec.h"

#include "emscripten.h"
#include "lexer_dedent.h"
#include "library.h"
#include "proxy_c.h"

// This counter tracks the current depth of calls into C code that originated
// externally, ie from JavaScript.  When the counter is 0 that corresponds to
// the top-level call into C.
#if MICROPY_GC_SPLIT_HEAP_AUTO
static size_t external_call_depth = 0;
#endif

// Emscripten defaults to a 64k C-stack, so our limit should be less than that.
#define CSTACK_SIZE (32 * 1024)

#if MICROPY_GC_SPLIT_HEAP_AUTO
static void gc_collect_top_level(mp_obj_t root_obj);
#endif

void external_call_depth_inc(void) {
    #if MICROPY_GC_SPLIT_HEAP_AUTO
    ++external_call_depth;
    #endif
}

void external_call_depth_dec(mp_obj_t root_obj) {
    #if MICROPY_GC_SPLIT_HEAP_AUTO
    --external_call_depth;
    if (external_call_depth == 0) {
        gc_collect_top_level(root_obj);
    }
    #endif
}

void mp_js_init(int pystack_size, int heap_size) {
    mp_cstack_init_with_sp_here(CSTACK_SIZE);

    #if MICROPY_ENABLE_PYSTACK
    mp_obj_t *pystack = (mp_obj_t *)malloc(pystack_size * sizeof(mp_obj_t));
    mp_pystack_init(pystack, pystack + pystack_size);
    #endif

    #if MICROPY_ENABLE_GC
    char *heap = (char *)malloc(heap_size * sizeof(char));
    gc_init(heap, heap + heap_size);
    #endif

    #if MICROPY_GC_SPLIT_HEAP_AUTO
    // When MICROPY_GC_SPLIT_HEAP_AUTO is enabled, set the GC threshold to a low
    // value so that a collection is triggered before the heap fills up.  The actual
    // garbage collection will happen later when control returns to the top-level,
    // via the `gc_collect_pending` flag and `gc_collect_top_level()`.
    MP_STATE_MEM(gc_alloc_threshold) = 16 * 1024 / MICROPY_BYTES_PER_GC_BLOCK;
    #endif

    mp_init();

    #if MICROPY_VFS_POSIX
    {
        // Mount the host FS at the root of our internal VFS
        mp_obj_t args[2] = {
            MP_OBJ_TYPE_GET_SLOT(&mp_type_vfs_posix, make_new)(&mp_type_vfs_posix, 0, 0, NULL),
            MP_OBJ_NEW_QSTR(qstr_from_str("/")),
        };
        mp_vfs_mount(2, args, (mp_map_t *)&mp_const_empty_map);
        MP_STATE_VM(vfs_cur) = MP_STATE_VM(vfs_mount_table);
    }
    mp_obj_list_append(mp_sys_path, MP_OBJ_NEW_QSTR(MP_QSTR__slash_lib));
    #endif
}

void mp_js_register_js_module(const char *name, uint32_t *value) {
    mp_obj_t module_name = MP_OBJ_NEW_QSTR(qstr_from_str(name));
    mp_obj_t module = proxy_convert_js_to_mp_obj_cside(value);
    mp_map_t *mp_loaded_modules_map = &MP_STATE_VM(mp_loaded_modules_dict).map;
    mp_map_lookup(mp_loaded_modules_map, module_name, MP_MAP_LOOKUP_ADD_IF_NOT_FOUND)->value = module;
}

void mp_js_do_import(const char *name, uint32_t *out) {
    external_call_depth_inc();
    nlr_buf_t nlr;
    if (nlr_push(&nlr) == 0) {
        mp_obj_t ret = mp_import_name(qstr_from_str(name), mp_const_none, MP_OBJ_NEW_SMALL_INT(0));
        // Return the leaf of the import, eg for "a.b.c" return "c".
        const char *m = name;
        const char *n = name;
        for (;; ++n) {
            if (*n == '\0' || *n == '.') {
                if (m != name) {
                    ret = mp_load_attr(ret, qstr_from_strn(m, n - m));
                }
                m = n + 1;
                if (*n == '\0') {
                    break;
                }
            }
        }
        nlr_pop();
        proxy_convert_mp_to_js_obj_cside(ret, out);
        external_call_depth_dec(ret);
    } else {
        // uncaught exception
        proxy_convert_mp_to_js_exc_cside(nlr.ret_val, out);
        external_call_depth_dec(nlr.ret_val);
    }
}

void mp_js_do_exec(const char *src, size_t len, uint32_t *out) {
    external_call_depth_inc();
    mp_parse_input_kind_t input_kind = MP_PARSE_FILE_INPUT;
    nlr_buf_t nlr;
    if (nlr_push(&nlr) == 0) {
        mp_lexer_t *lex = mp_lexer_new_from_str_len_dedent(MP_QSTR__lt_stdin_gt_, src, len, 0);
        qstr source_name = lex->source_name;
        mp_parse_tree_t parse_tree = mp_parse(lex, input_kind);
        mp_obj_t module_fun = mp_compile(&parse_tree, source_name, false);
        mp_obj_t ret = mp_call_function_0(module_fun);
        nlr_pop();
        proxy_convert_mp_to_js_obj_cside(ret, out);
        external_call_depth_dec(ret);
    } else {
        // uncaught exception
        proxy_convert_mp_to_js_exc_cside(nlr.ret_val, out);
        external_call_depth_dec(nlr.ret_val);
    }
}

void mp_js_do_exec_async(const char *src, size_t len, uint32_t *out) {
    mp_compile_allow_top_level_await = true;
    mp_js_do_exec(src, len, out);
    mp_compile_allow_top_level_await = false;
}

void mp_js_repl_init(void) {
    pyexec_event_repl_init();
}

int mp_js_repl_process_char(int c) {
    external_call_depth_inc();
    int ret = pyexec_event_repl_process_char(c);
    external_call_depth_dec(MP_OBJ_NULL);
    return ret;
}

#if MICROPY_GC_SPLIT_HEAP_AUTO

static bool gc_collect_pending = false;

// The largest new region that is available to become Python heap.
size_t gc_get_max_new_split(void) {
    return 128 * 1024 * 1024;
}

// Don't collect anything.  Instead require the heap to grow.
void gc_collect(void) {
    gc_collect_pending = true;
}

// Collect at the top-level, where there are no root pointers from stack/registers.
static void gc_collect_top_level(mp_obj_t root_obj) {
    if (gc_collect_pending) {
        gc_collect_pending = false;
        gc_collect_start();
        gc_collect_root(&root_obj, 1);
        gc_collect_end();
    }
}

#else

static void gc_scan_func(void *begin, void *end) {
    gc_collect_root((void **)begin, (void **)end - (void **)begin + 1);
}

void gc_collect(void) {
    gc_collect_start();
    emscripten_scan_stack(gc_scan_func);
    emscripten_scan_registers(gc_scan_func);
    gc_collect_end();
}

#endif

#if !MICROPY_VFS
mp_lexer_t *mp_lexer_new_from_file(qstr filename) {
    mp_raise_OSError(MP_ENOENT);
}

mp_import_stat_t mp_import_stat(const char *path) {
    return MP_IMPORT_STAT_NO_EXIST;
}

mp_obj_t mp_builtin_open(size_t n_args, const mp_obj_t *args, mp_map_t *kwargs) {
    return mp_const_none;
}
MP_DEFINE_CONST_FUN_OBJ_KW(mp_builtin_open_obj, 1, mp_builtin_open);
#endif

void nlr_jump_fail(void *val) {
    while (1) {
        ;
    }
}

void MP_NORETURN __fatal_error(const char *msg) {
    while (1) {
        ;
    }
}

#ifndef NDEBUG
void MP_WEAK __assert_func(const char *file, int line, const char *func, const char *expr) {
    printf("Assertion '%s' failed, at file %s:%d\n", expr, file, line);
    __fatal_error("Assertion failed");
}
#endif
