#include "first.h"

/**
 * the network chunk-API
 *
 *
 */

#include "chunk.h"
#include "base.h"
#include "log.h"

#include <sys/types.h>
#include <sys/stat.h>
#include "sys-mmap.h"

#include <stdlib.h>
#include <fcntl.h>
#include <unistd.h>

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

/* default 1MB, upper limit 128MB */
#define DEFAULT_TEMPFILE_SIZE (1 * 1024 * 1024)
#define MAX_TEMPFILE_SIZE (128 * 1024 * 1024)

static array *chunkqueue_default_tempdirs = NULL;
static unsigned int chunkqueue_default_tempfile_size = DEFAULT_TEMPFILE_SIZE;

chunkqueue *chunkqueue_init(void) {
	chunkqueue *cq;

	cq = calloc(1, sizeof(*cq));
	force_assert(NULL != cq);

	cq->first = NULL;
	cq->last = NULL;

	cq->unused = NULL;

	cq->tempdirs              = chunkqueue_default_tempdirs;
	cq->upload_temp_file_size = chunkqueue_default_tempfile_size;

	return cq;
}

static chunk *chunk_init(void) {
	chunk *c;

	c = calloc(1, sizeof(*c));
	force_assert(NULL != c);

	c->type = MEM_CHUNK;
	c->mem = buffer_init();
	c->file.name = buffer_init();
	c->file.start = c->file.length = c->file.mmap.offset = 0;
	c->file.fd = -1;
	c->file.mmap.start = MAP_FAILED;
	c->file.mmap.length = 0;
	c->file.is_temp = 0;
	c->offset = 0;
	c->next = NULL;

	return c;
}

static void chunk_reset(chunk *c) {
	if (NULL == c) return;

	c->type = MEM_CHUNK;

	buffer_reset(c->mem);

	if (c->file.is_temp && !buffer_string_is_empty(c->file.name)) {
		unlink(c->file.name->ptr);
	}

	buffer_reset(c->file.name);

	if (c->file.fd != -1) {
		close(c->file.fd);
		c->file.fd = -1;
	}
	if (MAP_FAILED != c->file.mmap.start) {
		munmap(c->file.mmap.start, c->file.mmap.length);
		c->file.mmap.start = MAP_FAILED;
	}
	c->file.start = c->file.length = c->file.mmap.offset = 0;
	c->file.mmap.length = 0;
	c->file.is_temp = 0;
	c->offset = 0;
	c->next = NULL;
}

static void chunk_free(chunk *c) {
	if (NULL == c) return;

	chunk_reset(c);

	buffer_free(c->mem);
	buffer_free(c->file.name);

	free(c);
}

static off_t chunk_remaining_length(const chunk *c) {
	off_t len = 0;
	switch (c->type) {
	case MEM_CHUNK:
		len = buffer_string_length(c->mem);
		break;
	case FILE_CHUNK:
		len = c->file.length;
		break;
	default:
		force_assert(c->type == MEM_CHUNK || c->type == FILE_CHUNK);
		break;
	}
	force_assert(c->offset <= len);
	return len - c->offset;
}

void chunkqueue_free(chunkqueue *cq) {
	chunk *c, *pc;

	if (NULL == cq) return;

	for (c = cq->first; c; ) {
		pc = c;
		c = c->next;
		chunk_free(pc);
	}

	for (c = cq->unused; c; ) {
		pc = c;
		c = c->next;
		chunk_free(pc);
	}

	free(cq);
}

static void chunkqueue_push_unused_chunk(chunkqueue *cq, chunk *c) {
	force_assert(NULL != cq && NULL != c);

	/* keep at max 4 chunks in the 'unused'-cache */
	if (cq->unused_chunks > 4) {
		chunk_free(c);
	} else {
		chunk_reset(c);
		c->next = cq->unused;
		cq->unused = c;
		cq->unused_chunks++;
	}
}

static chunk *chunkqueue_get_unused_chunk(chunkqueue *cq) {
	chunk *c;

	force_assert(NULL != cq);

	/* check if we have a unused chunk */
	if (0 == cq->unused) {
		c = chunk_init();
	} else {
		/* take the first element from the list (a stack) */
		c = cq->unused;
		cq->unused = c->next;
		c->next = NULL;
		cq->unused_chunks--;
	}

	return c;
}

static void chunkqueue_prepend_chunk(chunkqueue *cq, chunk *c) {
	c->next = cq->first;
	cq->first = c;

	if (NULL == cq->last) {
		cq->last = c;
	}
	cq->bytes_in += chunk_remaining_length(c);
}

static void chunkqueue_append_chunk(chunkqueue *cq, chunk *c) {
	c->next = NULL;
	if (cq->last) {
		cq->last->next = c;
	}
	cq->last = c;

	if (NULL == cq->first) {
		cq->first = c;
	}
	cq->bytes_in += chunk_remaining_length(c);
}

void chunkqueue_reset(chunkqueue *cq) {
	chunk *cur = cq->first;

	cq->first = cq->last = NULL;

	while (NULL != cur) {
		chunk *next = cur->next;
		chunkqueue_push_unused_chunk(cq, cur);
		cur = next;
	}

	cq->bytes_in = 0;
	cq->bytes_out = 0;
	cq->tempdir_idx = 0;
}

void chunkqueue_append_file_fd(chunkqueue *cq, buffer *fn, int fd, off_t offset, off_t len) {
	chunk *c;

	if (0 == len) {
		close(fd);
		return;
	}

	c = chunkqueue_get_unused_chunk(cq);

	c->type = FILE_CHUNK;

	buffer_copy_buffer(c->file.name, fn);
	c->file.start = offset;
	c->file.length = len;
	c->file.fd = fd;
	c->offset = 0;

	chunkqueue_append_chunk(cq, c);
}

void chunkqueue_append_file(chunkqueue *cq, buffer *fn, off_t offset, off_t len) {
	chunk *c;

	if (0 == len) return;

	c = chunkqueue_get_unused_chunk(cq);

	c->type = FILE_CHUNK;

	buffer_copy_buffer(c->file.name, fn);
	c->file.start = offset;
	c->file.length = len;
	c->offset = 0;

	chunkqueue_append_chunk(cq, c);
}

void chunkqueue_append_buffer(chunkqueue *cq, buffer *mem) {
	chunk *c;

	if (buffer_string_is_empty(mem)) return;

	c = chunkqueue_get_unused_chunk(cq);
	c->type = MEM_CHUNK;
	force_assert(NULL != c->mem);
	buffer_move(c->mem, mem);

	chunkqueue_append_chunk(cq, c);
}

void chunkqueue_prepend_buffer(chunkqueue *cq, buffer *mem) {
	chunk *c;

	if (buffer_string_is_empty(mem)) return;

	c = chunkqueue_get_unused_chunk(cq);
	c->type = MEM_CHUNK;
	force_assert(NULL != c->mem);
	buffer_move(c->mem, mem);

	chunkqueue_prepend_chunk(cq, c);
}


void chunkqueue_append_mem(chunkqueue *cq, const char * mem, size_t len) {
	chunk *c;

	if (0 == len) return;

	c = chunkqueue_get_unused_chunk(cq);
	c->type = MEM_CHUNK;
	buffer_copy_string_len(c->mem, mem, len);

	chunkqueue_append_chunk(cq, c);
}


void chunkqueue_append_chunkqueue(chunkqueue *cq, chunkqueue *src) {
	if (src == NULL || NULL == src->first) return;

	if (NULL == cq->first) {
		cq->first = src->first;
	} else {
		cq->last->next = src->first;
	}
	cq->last = src->last;
	cq->bytes_in += (src->bytes_in - src->bytes_out);

	src->first = NULL;
	src->last = NULL;
	src->bytes_out = src->bytes_in;
}


void chunkqueue_get_memory(chunkqueue *cq, char **mem, size_t *len, size_t min_size, size_t alloc_size) {
	static const size_t REALLOC_MAX_SIZE = 256;
	chunk *c;
	buffer *b;
	char *dummy_mem;
	size_t dummy_len;

	force_assert(NULL != cq);
	if (NULL == mem) mem = &dummy_mem;
	if (NULL == len) len = &dummy_len;

	/* default values: */
	if (0 == min_size) min_size = 1024;
	if (0 == alloc_size) alloc_size = 4096;
	if (alloc_size < min_size) alloc_size = min_size;

	if (NULL != cq->last && MEM_CHUNK == cq->last->type) {
		size_t have;

		b = cq->last->mem;
		have = buffer_string_space(b);

		/* unused buffer: allocate space */
		if (buffer_string_is_empty(b)) {
			buffer_string_prepare_copy(b, alloc_size);
			have = buffer_string_space(b);
		}
		/* if buffer is really small just make it bigger */
		else if (have < min_size && b->size <= REALLOC_MAX_SIZE) {
			size_t cur_len = buffer_string_length(b);
			size_t new_size = cur_len + min_size, append;
			if (new_size < alloc_size) new_size = alloc_size;

			append = new_size - cur_len;
			if (append >= min_size) {
				buffer_string_prepare_append(b, append);
				have = buffer_string_space(b);
			}
		}

		/* return pointer into existing buffer if large enough */
		if (have >= min_size) {
			*mem = b->ptr + buffer_string_length(b);
			*len = have;
			return;
		}
	}

	/* allocate new chunk */
	c = chunkqueue_get_unused_chunk(cq);
	c->type = MEM_CHUNK;
	chunkqueue_append_chunk(cq, c);

	b = c->mem;
	buffer_string_prepare_append(b, alloc_size);

	*mem = b->ptr + buffer_string_length(b);
	*len = buffer_string_space(b);
}

void chunkqueue_use_memory(chunkqueue *cq, size_t len) {
	buffer *b;

	force_assert(NULL != cq);
	force_assert(NULL != cq->last && MEM_CHUNK == cq->last->type);
	b = cq->last->mem;

	if (len > 0) {
		buffer_commit(b, len);
		cq->bytes_in += len;
	} else if (buffer_string_is_empty(b)) {
		/* unused buffer: can't remove chunk easily from
		 * end of list, so just reset the buffer
		 */
		buffer_reset(b);
	}
}

void chunkqueue_set_tempdirs_default (array *tempdirs, unsigned int upload_temp_file_size) {
	chunkqueue_default_tempdirs = tempdirs;
	chunkqueue_default_tempfile_size
		= (0 == upload_temp_file_size)                ? DEFAULT_TEMPFILE_SIZE
		: (upload_temp_file_size > MAX_TEMPFILE_SIZE) ? MAX_TEMPFILE_SIZE
		                                              : upload_temp_file_size;
}

#if 0
void chunkqueue_set_tempdirs(chunkqueue *cq, array *tempdirs, unsigned int upload_temp_file_size) {
	force_assert(NULL != cq);
	cq->tempdirs = tempdirs;
	cq->upload_temp_file_size
		= (0 == upload_temp_file_size)                ? DEFAULT_TEMPFILE_SIZE
		: (upload_temp_file_size > MAX_TEMPFILE_SIZE) ? MAX_TEMPFILE_SIZE
		                                              : upload_temp_file_size;
	cq->tempdir_idx = 0;
}
#endif

void chunkqueue_steal(chunkqueue *dest, chunkqueue *src, off_t len) {
	while (len > 0) {
		chunk *c = src->first;
		off_t clen = 0, use;

		if (NULL == c) break;

		clen = chunk_remaining_length(c);
		if (0 == clen) {
			/* drop empty chunk */
			src->first = c->next;
			if (c == src->last) src->last = NULL;
			chunkqueue_push_unused_chunk(src, c);
			continue;
		}

		use = len >= clen ? clen : len;
		len -= use;

		if (use == clen) {
			/* move complete chunk */
			src->first = c->next;
			if (c == src->last) src->last = NULL;

			chunkqueue_append_chunk(dest, c);
		} else {
			/* partial chunk with length "use" */

			switch (c->type) {
			case MEM_CHUNK:
				chunkqueue_append_mem(dest, c->mem->ptr + c->offset, use);
				break;
			case FILE_CHUNK:
				/* tempfile flag is in "last" chunk after the split */
				chunkqueue_append_file(dest, c->file.name, c->file.start + c->offset, use);
				break;
			}

			c->offset += use;
			force_assert(0 == len);
		}

		src->bytes_out += use;
	}
}

static chunk *chunkqueue_get_append_tempfile(chunkqueue *cq) {
	chunk *c;
	buffer *template = buffer_init_string("/var/tmp/lighttpd-upload-XXXXXX");
	int fd = -1;

	if (cq->tempdirs && cq->tempdirs->used) {
		/* we have several tempdirs, only if all of them fail we jump out */

		for (errno = EIO; cq->tempdir_idx < cq->tempdirs->used; ++cq->tempdir_idx) {
			data_string *ds = (data_string *)cq->tempdirs->data[cq->tempdir_idx];

			buffer_copy_buffer(template, ds->value);
			buffer_append_slash(template);
			buffer_append_string_len(template, CONST_STR_LEN("lighttpd-upload-XXXXXX"));

			if (-1 != (fd = mkstemp(template->ptr))) break;
		}
	} else {
		fd = mkstemp(template->ptr);
	}

	if (fd < 0) {
		buffer_free(template);
		return NULL;
	}

	c = chunkqueue_get_unused_chunk(cq);
	c->type = FILE_CHUNK;
	c->file.fd = fd;
	c->file.is_temp = 1;
	buffer_copy_buffer(c->file.name, template);
	c->file.length = 0;

	chunkqueue_append_chunk(cq, c);

	buffer_free(template);

	return c;
}

static void chunkqueue_remove_empty_chunks(chunkqueue *cq);

int chunkqueue_append_mem_to_tempfile(server *srv, chunkqueue *dest, const char *mem, size_t len) {
	chunk *dst_c;
	ssize_t written;

	do {
		/*
		 * if the last chunk is
		 * - smaller than dest->upload_temp_file_size
		 * - not read yet (offset == 0)
		 * -> append to it (so it might actually become larger than dest->upload_temp_file_size)
		 * otherwise
		 * -> create a new chunk
		 *
		 * */

		dst_c = dest->last;
		if (NULL != dst_c
			&& FILE_CHUNK == dst_c->type
			&& dst_c->file.is_temp
			&& dst_c->file.fd >= 0
			&& 0 == dst_c->offset) {
			/* ok, take the last chunk for our job */

			if (dst_c->file.length >= (off_t)dest->upload_temp_file_size) {
				/* the chunk is too large now, close it */
				int rc = close(dst_c->file.fd);
				dst_c->file.fd = -1;
				if (0 != rc) {
					log_error_write(srv, __FILE__, __LINE__, "sbss",
						"close() temp-file", dst_c->file.name, "failed:",
						strerror(errno));
					return -1;
				}
				dst_c = NULL;
			}
		} else {
			dst_c = NULL;
		}

		if (NULL == dst_c && NULL == (dst_c = chunkqueue_get_append_tempfile(dest))) {
			/* we don't have file to write to,
			 * EACCES might be one reason.
			 *
			 * Instead of sending 500 we send 413 and say the request is too large
			 */

			log_error_write(srv, __FILE__, __LINE__, "ss",
				"opening temp-file failed:", strerror(errno));

			return -1;
		}

		written = write(dst_c->file.fd, mem, len);

		if ((size_t) written == len) {
			dst_c->file.length += len;
			dest->bytes_in += len;

			return 0;
		} else if (written >= 0) {
			/*(assume EINTR if partial write and retry write();
			 * retry write() might fail with ENOSPC if no more space on volume)*/
			dest->bytes_in += written;
			mem += written;
			len -= (size_t)written;
			dst_c->file.length += (size_t)written;
			/* continue; retry */
		} else if (errno == EINTR) {
			/* continue; retry */
		} else {
			int retry = (errno == ENOSPC && dest->tempdirs && ++dest->tempdir_idx < dest->tempdirs->used);
			if (!retry) {
				log_error_write(srv, __FILE__, __LINE__, "sbs",
						"write() temp-file", dst_c->file.name, "failed:",
						strerror(errno));
			}

			if (0 == chunk_remaining_length(dst_c)) {
				/*(remove empty chunk and unlink tempfile)*/
				chunkqueue_remove_empty_chunks(dest);
			} else {/*(close tempfile; avoid later attempts to append)*/
				int rc = close(dst_c->file.fd);
				dst_c->file.fd = -1;
				if (0 != rc) {
					log_error_write(srv, __FILE__, __LINE__, "sbss",
						"close() temp-file", dst_c->file.name, "failed:",
						strerror(errno));
					return -1;
				}
			}
			if (!retry) return -1;

			/* continue; retry */
		}

	} while (dst_c);

	return -1; /*(not reached)*/
}

int chunkqueue_steal_with_tempfiles(server *srv, chunkqueue *dest, chunkqueue *src, off_t len) {
	while (len > 0) {
		chunk *c = src->first;
		off_t clen = 0, use;

		if (NULL == c) break;

		clen = chunk_remaining_length(c);
		if (0 == clen) {
			/* drop empty chunk */
			src->first = c->next;
			if (c == src->last) src->last = NULL;
			chunkqueue_push_unused_chunk(src, c);
			continue;
		}

		use = (len >= clen) ? clen : len;
		len -= use;

		switch (c->type) {
		case FILE_CHUNK:
			if (use == clen) {
				/* move complete chunk */
				src->first = c->next;
				if (c == src->last) src->last = NULL;
				chunkqueue_append_chunk(dest, c);
			} else {
				/* partial chunk with length "use" */
				/* tempfile flag is in "last" chunk after the split */
				chunkqueue_append_file(dest, c->file.name, c->file.start + c->offset, use);

				c->offset += use;
				force_assert(0 == len);
			}
			break;

		case MEM_CHUNK:
			/* store "use" bytes from memory chunk in tempfile */
			if (0 != chunkqueue_append_mem_to_tempfile(srv, dest, c->mem->ptr + c->offset, use)) {
				return -1;
			}

			if (use == clen) {
				/* finished chunk */
				src->first = c->next;
				if (c == src->last) src->last = NULL;
				chunkqueue_push_unused_chunk(src, c);
			} else {
				/* partial chunk */
				c->offset += use;
				force_assert(0 == len);
			}
			break;
		}

		src->bytes_out += use;
	}

	return 0;
}

off_t chunkqueue_length(chunkqueue *cq) {
	off_t len = 0;
	chunk *c;

	for (c = cq->first; c; c = c->next) {
		len += chunk_remaining_length(c);
	}

	return len;
}

int chunkqueue_is_empty(chunkqueue *cq) {
	return NULL == cq->first;
}

void chunkqueue_mark_written(chunkqueue *cq, off_t len) {
	off_t written = len;
	chunk *c;
	force_assert(len >= 0);

	for (c = cq->first; NULL != c; c = cq->first) {
		off_t c_len = chunk_remaining_length(c);

		if (0 == written && 0 != c_len) break; /* no more finished chunks */

		if (written >= c_len) { /* chunk got finished */
			c->offset += c_len;
			written -= c_len;

			cq->first = c->next;
			if (c == cq->last) cq->last = NULL;

			chunkqueue_push_unused_chunk(cq, c);
		} else { /* partial chunk */
			c->offset += written;
			written = 0;
			break; /* chunk not finished */
		}
	}

	force_assert(0 == written);
	cq->bytes_out += len;
}

void chunkqueue_remove_finished_chunks(chunkqueue *cq) {
	chunk *c;

	for (c = cq->first; c; c = cq->first) {
		if (0 != chunk_remaining_length(c)) break; /* not finished yet */

		cq->first = c->next;
		if (c == cq->last) cq->last = NULL;

		chunkqueue_push_unused_chunk(cq, c);
	}
}

static void chunkqueue_remove_empty_chunks(chunkqueue *cq) {
	chunk *c;
	chunkqueue_remove_finished_chunks(cq);
	if (chunkqueue_is_empty(cq)) return;

	for (c = cq->first; c->next; c = c->next) {
		if (0 == chunk_remaining_length(c->next)) {
			chunk *empty = c->next;
			c->next = empty->next;
			if (empty == cq->last) cq->last = c;

			chunkqueue_push_unused_chunk(cq, empty);
		}
	}
}