/*
 * This file is part of the MicroPython project, http://micropython.org/
 *
 * The MIT License (MIT)
 *
 * Copyright (c) 2014 Damien P. George
 * Copyright (c) 2014-2016 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 <string.h>
#include <unistd.h>

#include "py/objstr.h"
#include "py/stream.h"
#include "py/runtime.h"

// This file defines generic Python stream read/write methods which
// dispatch to the underlying stream interface of an object.

// TODO: should be in mpconfig.h
#define DEFAULT_BUFFER_SIZE 256

STATIC mp_obj_t stream_readall(mp_obj_t self_in);

#define STREAM_CONTENT_TYPE(stream) (((stream)->is_text) ? &mp_type_str : &mp_type_bytes)

// Returns error condition in *errcode, if non-zero, return value is number of bytes written
// before error condition occurred. If *errcode == 0, returns total bytes written (which will
// be equal to input size).
mp_uint_t mp_stream_rw(mp_obj_t stream, void *buf_, mp_uint_t size, int *errcode, byte flags) {
 byte *buf = buf_;
 typedef mp_uint_t (*io_func_t)(mp_obj_t obj, void *buf, mp_uint_t size, int *errcode);
 io_func_t io_func;
 const mp_stream_p_t *stream_p = mp_get_stream(stream);
 if (flags & MP_STREAM_RW_WRITE) {
 io_func = (io_func_t)stream_p->write;
 } else {
 io_func = stream_p->read;
 }

 *errcode = 0;
 mp_uint_t done = 0;
 while (size > 0) {
 mp_uint_t out_sz = io_func(stream, buf, size, errcode);
 // For read, out_sz == 0 means EOF. For write, it's unspecified
 // what it means, but we don't make any progress, so returning
 // is still the best option.
 if (out_sz == 0) {
 return done;
 }
 if (out_sz == MP_STREAM_ERROR) {
 // If we read something before getting EAGAIN, don't leak it
 if (mp_is_nonblocking_error(*errcode) && done != 0) {
 *errcode = 0;
 }
 return done;
 }
 if (flags & MP_STREAM_RW_ONCE) {
 return out_sz;
 }

 buf += out_sz;
 size -= out_sz;
 done += out_sz;
 }
 return done;
}

const mp_stream_p_t *mp_get_stream_raise(mp_obj_t self_in, int flags) {
 const mp_obj_type_t *type = mp_obj_get_type(self_in);
 const mp_stream_p_t *stream_p = type->protocol;
 if (stream_p == NULL
 || ((flags & MP_STREAM_OP_READ) && stream_p->read == NULL)
 || ((flags & MP_STREAM_OP_WRITE) && stream_p->write == NULL)
 || ((flags & MP_STREAM_OP_IOCTL) && stream_p->ioctl == NULL)) {
 // CPython: io.UnsupportedOperation, OSError subclass
 mp_raise_msg(&mp_type_OSError, MP_ERROR_TEXT("stream operation not supported"));
 }
 return stream_p;
}

STATIC mp_obj_t stream_read_generic(size_t n_args, const mp_obj_t *args, byte flags) {
 // What to do if sz < -1? Python docs don't specify this case.
 // CPython does a readall, but here we silently let negatives through,
 // and they will cause a MemoryError.
 mp_int_t sz;
 if (n_args == 1 || ((sz = mp_obj_get_int(args[1])) == -1)) {
 return stream_readall(args[0]);
 }

 const mp_stream_p_t *stream_p = mp_get_stream(args[0]);

 #if MICROPY_PY_BUILTINS_STR_UNICODE
 if (stream_p->is_text) {
 // We need to read sz number of unicode characters. Because we don't have any
 // buffering, and because the stream API can only read bytes, we must read here
 // in units of bytes and must never over read. If we want sz chars, then reading
 // sz bytes will never over-read, so we follow this approach, in a loop to keep
 // reading until we have exactly enough chars. This will be 1 read for text
 // with ASCII-only chars, and about 2 reads for text with a couple of non-ASCII
 // chars. For text with lots of non-ASCII chars, it'll be pretty inefficient
 // in time and memory.

 vstr_t vstr;
 vstr_init(&vstr, sz);
 mp_uint_t more_bytes = sz;
 mp_uint_t last_buf_offset = 0;
 while (more_bytes > 0) {
 char *p = vstr_add_len(&vstr, more_bytes);
 int error;
 mp_uint_t out_sz = mp_stream_read_exactly(args[0], p, more_bytes, &error);
 if (error != 0) {
 vstr_cut_tail_bytes(&vstr, more_bytes);
 if (mp_is_nonblocking_error(error)) {
 // With non-blocking streams, we read as much as we can.
 // If we read nothing, return None, just like read().
 // Otherwise, return data read so far.
 // TODO what if we have read only half a non-ASCII char?
 if (vstr.len == 0) {
 vstr_clear(&vstr);
 return mp_const_none;
 }
 break;
 }
 mp_raise_OSError(error);
 }

 if (out_sz < more_bytes) {
 // Finish reading.
 // TODO what if we have read only half a non-ASCII char?
 vstr_cut_tail_bytes(&vstr, more_bytes - out_sz);
 if (out_sz == 0) {
 break;
 }
 }

 // count chars from bytes just read
 for (mp_uint_t off = last_buf_offset;;) {
 byte b = vstr.buf[off];
 int n;
 if (!UTF8_IS_NONASCII(b)) {
 // 1-byte ASCII char
 n = 1;
 } else if ((b & 0xe0) == 0xc0) {
 // 2-byte char
 n = 2;
 } else if ((b & 0xf0) == 0xe0) {
 // 3-byte char
 n = 3;
 } else if ((b & 0xf8) == 0xf0) {
 // 4-byte char
 n = 4;
 } else {
 // TODO
 n = 5;
 }
 if (off + n <= vstr.len) {
 // got a whole char in n bytes
 off += n;
 sz -= 1;
 last_buf_offset = off;
 if (off >= vstr.len) {
 more_bytes = sz;
 break;
 }
 } else {
 // didn't get a whole char, so work out how many extra bytes are needed for
 // this partial char, plus bytes for additional chars that we want
 more_bytes = (off + n - vstr.len) + (sz - 1);
 break;
 }
 }
 }

 return mp_obj_new_str_from_vstr(&mp_type_str, &vstr);
 }
 #endif

 vstr_t vstr;
 vstr_init_len(&vstr, sz);
 int error;
 mp_uint_t out_sz = mp_stream_rw(args[0], vstr.buf, sz, &error, flags);
 if (error != 0) {
 vstr_clear(&vstr);
 if (mp_is_nonblocking_error(error)) {
 // https://docs.python.org/3.4/library/io.html#io.RawIOBase.read
 // "If the object is in non-blocking mode and no bytes are available,
 // None is returned."
 // This is actually very weird, as naive truth check will treat
 // this as EOF.
 return mp_const_none;
 }
 mp_raise_OSError(error);
 } else {
 vstr.len = out_sz;
 return mp_obj_new_str_from_vstr(STREAM_CONTENT_TYPE(stream_p), &vstr);
 }
}

STATIC mp_obj_t stream_read(size_t n_args, const mp_obj_t *args) {
 return stream_read_generic(n_args, args, MP_STREAM_RW_READ);
}
MP_DEFINE_CONST_FUN_OBJ_VAR_BETWEEN(mp_stream_read_obj, 1, 2, stream_read);

STATIC mp_obj_t stream_read1(size_t n_args, const mp_obj_t *args) {
 return stream_read_generic(n_args, args, MP_STREAM_RW_READ | MP_STREAM_RW_ONCE);
}
MP_DEFINE_CONST_FUN_OBJ_VAR_BETWEEN(mp_stream_read1_obj, 1, 2, stream_read1);

mp_obj_t mp_stream_write(mp_obj_t self_in, const void *buf, size_t len, byte flags) {
 int error;
 mp_uint_t out_sz = mp_stream_rw(self_in, (void *)buf, len, &error, flags);
 if (error != 0) {
 if (mp_is_nonblocking_error(error)) {
 // http://docs.python.org/3/library/io.html#io.RawIOBase.write
 // "None is returned if the raw stream is set not to block and
 // no single byte could be readily written to it."
 return mp_const_none;
 }
 mp_raise_OSError(error);
 } else {
 return MP_OBJ_NEW_SMALL_INT(out_sz);
 }
}

// This is used to adapt a stream object to an mp_print_t interface
void mp_stream_write_adaptor(void *self, const char *buf, size_t len) {
 mp_stream_write(MP_OBJ_FROM_PTR(self), buf, len, MP_STREAM_RW_WRITE);
}

STATIC mp_obj_t stream_write_method(size_t n_args, const mp_obj_t *args) {
 mp_buffer_info_t bufinfo;
 mp_get_buffer_raise(args[1], &bufinfo, MP_BUFFER_READ);
 size_t max_len = (size_t)-1;
 size_t off = 0;
 if (n_args == 3) {
 max_len = mp_obj_get_int_truncated(args[2]);
 } else if (n_args == 4) {
 off = mp_obj_get_int_truncated(args[2]);
 max_len = mp_obj_get_int_truncated(args[3]);
 if (off > bufinfo.len) {
 off = bufinfo.len;
 }
 }
 bufinfo.len -= off;
 return mp_stream_write(args[0], (byte *)bufinfo.buf + off, MIN(bufinfo.len, max_len), MP_STREAM_RW_WRITE);
}
MP_DEFINE_CONST_FUN_OBJ_VAR_BETWEEN(mp_stream_write_obj, 2, 4, stream_write_method);

STATIC mp_obj_t stream_write1_method(mp_obj_t self_in, mp_obj_t arg) {
 mp_buffer_info_t bufinfo;
 mp_get_buffer_raise(arg, &bufinfo, MP_BUFFER_READ);
 return mp_stream_write(self_in, bufinfo.buf, bufinfo.len, MP_STREAM_RW_WRITE | MP_STREAM_RW_ONCE);
}
MP_DEFINE_CONST_FUN_OBJ_2(mp_stream_write1_obj, stream_write1_method);

STATIC mp_obj_t stream_readinto(size_t n_args, const mp_obj_t *args) {
 mp_buffer_info_t bufinfo;
 mp_get_buffer_raise(args[1], &bufinfo, MP_BUFFER_WRITE);

 // CPython extension: if 2nd arg is provided, that's max len to read,
 // instead of full buffer. Similar to
 // https://docs.python.org/3/library/socket.html#socket.socket.recv_into
 mp_uint_t len = bufinfo.len;
 if (n_args > 2) {
 len = mp_obj_get_int(args[2]);
 if (len > bufinfo.len) {
 len = bufinfo.len;
 }
 }

 int error;
 mp_uint_t out_sz = mp_stream_read_exactly(args[0], bufinfo.buf, len, &error);
 if (error != 0) {
 if (mp_is_nonblocking_error(error)) {
 return mp_const_none;
 }
 mp_raise_OSError(error);
 } else {
 return MP_OBJ_NEW_SMALL_INT(out_sz);
 }
}
MP_DEFINE_CONST_FUN_OBJ_VAR_BETWEEN(mp_stream_readinto_obj, 2, 3, stream_readinto);

STATIC mp_obj_t stream_readall(mp_obj_t self_in) {
 const mp_stream_p_t *stream_p = mp_get_stream(self_in);

 mp_uint_t total_size = 0;
 vstr_t vstr;
 vstr_init(&vstr, DEFAULT_BUFFER_SIZE);
 char *p = vstr.buf;
 mp_uint_t current_read = DEFAULT_BUFFER_SIZE;
 while (true) {
 int error;
 mp_uint_t out_sz = stream_p->read(self_in, p, current_read, &error);
 if (out_sz == MP_STREAM_ERROR) {
 if (mp_is_nonblocking_error(error)) {
 // With non-blocking streams, we read as much as we can.
 // If we read nothing, return None, just like read().
 // Otherwise, return data read so far.
 if (total_size == 0) {
 return mp_const_none;
 }
 break;
 }
 mp_raise_OSError(error);
 }
 if (out_sz == 0) {
 break;
 }
 total_size += out_sz;
 if (out_sz < current_read) {
 current_read -= out_sz;
 p += out_sz;
 } else {
 p = vstr_extend(&vstr, DEFAULT_BUFFER_SIZE);
 current_read = DEFAULT_BUFFER_SIZE;
 }
 }

 vstr.len = total_size;
 return mp_obj_new_str_from_vstr(STREAM_CONTENT_TYPE(stream_p), &vstr);
}

// Unbuffered, inefficient implementation of readline() for raw I/O files.
STATIC mp_obj_t stream_unbuffered_readline(size_t n_args, const mp_obj_t *args) {
 const mp_stream_p_t *stream_p = mp_get_stream(args[0]);

 mp_int_t max_size = -1;
 if (n_args > 1) {
 max_size = MP_OBJ_SMALL_INT_VALUE(args[1]);
 }

 vstr_t vstr;
 if (max_size != -1) {
 vstr_init(&vstr, max_size);
 } else {
 vstr_init(&vstr, 16);
 }

 while (max_size == -1 || max_size-- != 0) {
 char *p = vstr_add_len(&vstr, 1);
 int error;
 mp_uint_t out_sz = stream_p->read(args[0], p, 1, &error);
 if (out_sz == MP_STREAM_ERROR) {
 if (mp_is_nonblocking_error(error)) {
 if (vstr.len == 1) {
 // We just incremented it, but otherwise we read nothing
 // and immediately got EAGAIN. This case is not well
 // specified in
 // https://docs.python.org/3/library/io.html#io.IOBase.readline
 // unlike similar case for read(). But we follow the latter's
 // behavior - return None.
 vstr_clear(&vstr);
 return mp_const_none;
 } else {
 goto done;
 }
 }
 mp_raise_OSError(error);
 }
 if (out_sz == 0) {
 done:
 // Back out previously added byte
 // Consider, what's better - read a char and get OutOfMemory (so read
 // char is lost), or allocate first as we do.
 vstr_cut_tail_bytes(&vstr, 1);
 break;
 }
 if (*p == '\n') {
 break;
 }
 }

 return mp_obj_new_str_from_vstr(STREAM_CONTENT_TYPE(stream_p), &vstr);
}
MP_DEFINE_CONST_FUN_OBJ_VAR_BETWEEN(mp_stream_unbuffered_readline_obj, 1, 2, stream_unbuffered_readline);

// TODO take an optional extra argument (what does it do exactly?)
STATIC mp_obj_t stream_unbuffered_readlines(mp_obj_t self) {
 mp_obj_t lines = mp_obj_new_list(0, NULL);
 for (;;) {
 mp_obj_t line = stream_unbuffered_readline(1, &self);
 if (!mp_obj_is_true(line)) {
 break;
 }
 mp_obj_list_append(lines, line);
 }
 return lines;
}
MP_DEFINE_CONST_FUN_OBJ_1(mp_stream_unbuffered_readlines_obj, stream_unbuffered_readlines);

mp_obj_t mp_stream_unbuffered_iter(mp_obj_t self) {
 mp_obj_t l_in = stream_unbuffered_readline(1, &self);
 if (mp_obj_is_true(l_in)) {
 return l_in;
 }
 return MP_OBJ_STOP_ITERATION;
}

mp_obj_t mp_stream_close(mp_obj_t stream) {
 const mp_stream_p_t *stream_p = mp_get_stream(stream);
 int error;
 mp_uint_t res = stream_p->ioctl(stream, MP_STREAM_CLOSE, 0, &error);
 if (res == MP_STREAM_ERROR) {
 mp_raise_OSError(error);
 }
 return mp_const_none;
}
MP_DEFINE_CONST_FUN_OBJ_1(mp_stream_close_obj, mp_stream_close);

STATIC mp_obj_t stream_seek(size_t n_args, const mp_obj_t *args) {
 struct mp_stream_seek_t seek_s;
 // TODO: Could be uint64
 seek_s.offset = mp_obj_get_int(args[1]);
 seek_s.whence = SEEK_SET;
 if (n_args == 3) {
 seek_s.whence = mp_obj_get_int(args[2]);
 }

 // In POSIX, it's error to seek before end of stream, we enforce it here.
 if (seek_s.whence == SEEK_SET && seek_s.offset < 0) {
 mp_raise_OSError(MP_EINVAL);
 }

 const mp_stream_p_t *stream_p = mp_get_stream(args[0]);
 int error;
 mp_uint_t res = stream_p->ioctl(args[0], MP_STREAM_SEEK, (mp_uint_t)(uintptr_t)&seek_s, &error);
 if (res == MP_STREAM_ERROR) {
 mp_raise_OSError(error);
 }

 // TODO: Could be uint64
 return mp_obj_new_int_from_uint(seek_s.offset);
}
MP_DEFINE_CONST_FUN_OBJ_VAR_BETWEEN(mp_stream_seek_obj, 2, 3, stream_seek);

STATIC mp_obj_t stream_tell(mp_obj_t self) {
 mp_obj_t offset = MP_OBJ_NEW_SMALL_INT(0);
 mp_obj_t whence = MP_OBJ_NEW_SMALL_INT(SEEK_CUR);
 const mp_obj_t args[3] = {self, offset, whence};
 return stream_seek(3, args);
}
MP_DEFINE_CONST_FUN_OBJ_1(mp_stream_tell_obj, stream_tell);

STATIC mp_obj_t stream_flush(mp_obj_t self) {
 const mp_stream_p_t *stream_p = mp_get_stream(self);
 int error;
 mp_uint_t res = stream_p->ioctl(self, MP_STREAM_FLUSH, 0, &error);
 if (res == MP_STREAM_ERROR) {
 mp_raise_OSError(error);
 }
 return mp_const_none;
}
MP_DEFINE_CONST_FUN_OBJ_1(mp_stream_flush_obj, stream_flush);

STATIC mp_obj_t stream_ioctl(size_t n_args, const mp_obj_t *args) {
 mp_buffer_info_t bufinfo;
 uintptr_t val = 0;
 if (n_args > 2) {
 if (mp_get_buffer(args[2], &bufinfo, MP_BUFFER_WRITE)) {
 val = (uintptr_t)bufinfo.buf;
 } else {
 val = mp_obj_get_int_truncated(args[2]);
 }
 }

 const mp_stream_p_t *stream_p = mp_get_stream(args[0]);
 int error;
 mp_uint_t res = stream_p->ioctl(args[0], mp_obj_get_int(args[1]), val, &error);
 if (res == MP_STREAM_ERROR) {
 mp_raise_OSError(error);
 }

 return mp_obj_new_int(res);
}
MP_DEFINE_CONST_FUN_OBJ_VAR_BETWEEN(mp_stream_ioctl_obj, 2, 3, stream_ioctl);

#if MICROPY_STREAMS_POSIX_API
/*
 * POSIX-like functions
 *
 * These functions have POSIX-compatible signature (except for "void *stream"
 * first argument instead of "int fd"). They are useful to port existing
 * POSIX-compatible software to work with MicroPython streams.
 */

#include <errno.h>

ssize_t mp_stream_posix_write(void *stream, const void *buf, size_t len) {
 mp_obj_base_t *o = stream;
 const mp_stream_p_t *stream_p = o->type->protocol;
 mp_uint_t out_sz = stream_p->write(MP_OBJ_FROM_PTR(stream), buf, len, &errno);
 if (out_sz == MP_STREAM_ERROR) {
 return -1;
 } else {
 return out_sz;
 }
}

ssize_t mp_stream_posix_read(void *stream, void *buf, size_t len) {
 mp_obj_base_t *o = stream;
 const mp_stream_p_t *stream_p = o->type->protocol;
 mp_uint_t out_sz = stream_p->read(MP_OBJ_FROM_PTR(stream), buf, len, &errno);
 if (out_sz == MP_STREAM_ERROR) {
 return -1;
 } else {
 return out_sz;
 }
}

off_t mp_stream_posix_lseek(void *stream, off_t offset, int whence) {
 const mp_obj_base_t *o = stream;
 const mp_stream_p_t *stream_p = o->type->protocol;
 struct mp_stream_seek_t seek_s;
 seek_s.offset = offset;
 seek_s.whence = whence;
 mp_uint_t res = stream_p->ioctl(MP_OBJ_FROM_PTR(stream), MP_STREAM_SEEK, (mp_uint_t)(uintptr_t)&seek_s, &errno);
 if (res == MP_STREAM_ERROR) {
 return -1;
 }
 return seek_s.offset;
}

int mp_stream_posix_fsync(void *stream) {
 mp_obj_base_t *o = stream;
 const mp_stream_p_t *stream_p = o->type->protocol;
 mp_uint_t res = stream_p->ioctl(MP_OBJ_FROM_PTR(stream), MP_STREAM_FLUSH, 0, &errno);
 if (res == MP_STREAM_ERROR) {
 return -1;
 }
 return res;
}

#endif