/*
 * $Id$
 *
 * MiniMIME - a library for handling MIME messages
 *
 * Copyright (C) 2003 Jann Fischer <rezine@mistrust.net>
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * 1. Redistributions of source code must retain the above copyright
 *	notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *	notice, this list of conditions and the following disclaimer in the
 *	documentation and/or other materials provided with the distribution.
 * 3. Neither the name of the author nor the names of the contributors
 *	may be used to endorse or promote products derived from this software
 *	without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY JANN FISCHER AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL JANN FISCHER OR THE VOICES IN HIS HEAD
 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF
 * THE POSSIBILITY OF SUCH DAMAGE.
 */
#include <sys/types.h>
#include <sys/stat.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <fcntl.h>
#include <ctype.h>
#include <assert.h>

#include "mm_internal.h"

/** @file mm_mimepart.c
 *
 * This module contains functions for manipulating MIME header objects.
 */

/** @defgroup mimepart Accessing and manipulating MIME parts 
 *
 * MIME parts, also called entities, represent the structure of a MIME
 * message. ``Normal'' internet messages have only a single part, and
 * are called ``flat'' messages. Multipart messages have more then one
 * part, and each MIME part can have it's own subset of headers.
 *
 * Provided here are functions to easily access all informations from
 * a MIME part, including their specific headers and bodies.
 */

/** @{ 
 * @name Creating and destroying MIME parts 
 */

/**
 * Allocates memory for a new mm_mimepart structure and initializes it.
 *
 * @return A pointer to a struct of type mm_mimeheader or NULL on failure
 * @see mm_mimepart_free
 * @note The memory must be freed by using mm_mimepart_free() later on.
 */
struct mm_mimepart *
mm_mimepart_new(void)
{
	struct mm_mimepart *part;

	part = (struct mm_mimepart *)xmalloc(sizeof(struct mm_mimepart));

	TAILQ_INIT(&part->headers);

	part->opaque_length = 0;
	part->opaque_body = NULL;
	
	part->length = 0;
	part->body = NULL;
	
	part->type = NULL;

	return part;
}

/**
 * Creates a MIME part from a file
 *
 * @param filename The name of the file to create the MIME part from
 * @return A pointer to a new MIME part object
 *
 * This function creates a new MIME part object from a file. The object should
 * be freed using mm_mimepart_free() later on. This function does NOT set the
 * Content-Type and neither does any encoding work.
 */
struct mm_mimepart *
mm_mimepart_fromfile(const char *filename)
{
	int fd;
	char *data;
	size_t r;
	struct stat st;
	struct mm_mimepart *part;

	mm_errno = MM_ERROR_NONE;

	if ((fd = open(filename, O_RDONLY)) == -1) {
		mm_errno = MM_ERROR_ERRNO;
		return NULL;
	}

	if ((stat(filename, &st)) == -1) {
		mm_errno = MM_ERROR_ERRNO;
		close(fd);
		return NULL;
	}

	data = xmalloc(st.st_size);
	r = read(fd, data, st.st_size);
	if (r != st.st_size) {
		mm_errno = MM_ERROR_ERRNO;
		close(fd);
		return(NULL);
	}

	data[r] = '\0';
	close(fd);

	part = mm_mimepart_new();
	part->length = r;
	part->body = data;

	return part;
}


/**
 * Frees all memory allocated by a mm_mimepart object.
 *
 * @param part A pointer to an allocated mm_mimepart object
 * @see mm_mimepart_new
 */
void
mm_mimepart_free(struct mm_mimepart *part)
{
	struct mm_mimeheader *header;

	assert(part != NULL);

	TAILQ_FOREACH(header, &part->headers, next) {
		mm_mimeheader_free(header);
		TAILQ_REMOVE(&part->headers, header, next);
	}

	if (part->opaque_body != NULL) {
		xfree(part->opaque_body);
		part->opaque_body = NULL;
		part->body = NULL;
	} else if (part->body != NULL) {
		xfree(part->body);
		part->body = NULL;
	}

	if (part->type != NULL) {
		mm_content_free(part->type);
		part->type = NULL;
	}

	xfree(part);
	part = NULL;
}

/** @} */

/** @{ 
 * @name Accessing the MIME part's mail header
 */

/**
 * Attaches a mm_mimeheader object to a MIME part
 *
 * @param part A valid MIME part object
 * @param header A valid MIME header object
 * @return 0 if successfull or -1 if the header could not be attached
 */
int
mm_mimepart_attachheader(struct mm_mimepart *part, struct mm_mimeheader *header)
{
	assert(part != NULL);
	assert(header != NULL);

	if (TAILQ_EMPTY(&part->headers)) {
		TAILQ_INSERT_HEAD(&part->headers, header, next);
	} else {
		TAILQ_INSERT_TAIL(&part->headers, header, next);
	}

	return(0);
}

/**
 * Retrieves the number of MIME headers available in a MIME part
 *
 * @param part A valid MIME part object
 * @return The number of MIME headers within the MIME part
 */
int
mm_mimepart_countheaders(struct mm_mimepart *part)
{
	int found;
	struct mm_mimeheader *header;

	assert(part != NULL);

	found = 0;

	TAILQ_FOREACH(header, &part->headers, next) {
		found++;
	}

	return found;
}

/**
 * Retrieves the number of MIME headers with a given name in a MIME part
 *
 * @param part A valid MIME part object
 * @param name The name of the MIME header which to count for
 * @return The number of MIME headers within the MIME part
 */
int
mm_mimepart_countheaderbyname(struct mm_mimepart *part, const char *name)
{
	int found;
	struct mm_mimeheader *header;

	assert(part != NULL);

	found = 0;

	TAILQ_FOREACH(header, &part->headers, next) {
		if (strcasecmp(header->name, name) == 0) {
			found++;
		}
	}

	return found;
}

/**
 * Get a MIME header object from a MIME part
 *
 * @param part A valid MIME part object
 * @param name The name of the MIME header which to retrieve
 * @param idx Which header field to get (in case of multiple headers of the
 *	      same name).
 * @return A pointer to the requested MIME header on success, or NULL if there
 *         either isn't a header with the requested name or idx is out of 
 *         range.
 */
struct mm_mimeheader *
mm_mimepart_getheaderbyname(struct mm_mimepart *part, const char *name, int idx)
{
	struct mm_mimeheader *header;
	int curidx;

	curidx = 0;

	TAILQ_FOREACH(header, &part->headers, next) {
		if (!strcasecmp(header->name, name)) {
			if (curidx == idx)
				return header;
			else
				curidx++;
		}
	}

	/* Not found */
	return NULL;
}

/**
 * Gets the value of a MIME header object
 *
 * @param part A valid MIME part object
 * @param name The name of the header field to get the value from
 * @param idx The index of the header field to get, in case there are multiple
 *            headers with the same name.
 * @return A pointer to the requested value on success, or NULL if there either
 *         isn't a header with the requested name or idx is out of range.
 *
 */
const char *
mm_mimepart_getheadervalue(struct mm_mimepart *part, const char *name, int idx)
{
	struct mm_mimeheader *header;

	header = mm_mimepart_getheaderbyname(part, name, idx);
	if (header == NULL)
		return NULL;
	else
		return header->value;
}

/**
 * Initializes a header loop for a given MIME part
 *
 * @param part A valid MIME part object
 * @param id The address of a MIME header object (to allow reentrance)
 * @return 0 on success or -1 on failure
 * @see mm_mimepart_headers_next
 * 
 * Looping through headers can be done in the following way:
 *
 * @code
 * struct mm_mimeheader *header, *lheader;
 *
 * mm_mimepart_headers_start(part, &lheader);
 *
 * while ((header = mm_mimepart_headers_next(part, &lheader)) != NULL) {
 *	printf("%s: %s\n", header->name, header->value);	
 * }
 *
 * @endcode
 *
 * For convienience, the macro mm_mimepart_headers_foreach() can be used to
 * loop through headers in a one-shot manner.
 */
int
mm_mimepart_headers_start(struct mm_mimepart *part, struct mm_mimeheader **id)
{
	assert(part != NULL);
	
	if (TAILQ_EMPTY(&part->headers)) {
		return -1;
	}
	*id = NULL;
	return 0;
}

/**
 * Returns the next MIME header of a given MIME part object
 *
 * @param part A valid MIME part object
 * @param id A previously initialized MIME header object
 * @return A pointer to the MIME header object or NULL if end of headers was
 * 	reached.
 * @see mm_mimepart_headers_start
 */
struct mm_mimeheader *
mm_mimepart_headers_next(struct mm_mimepart *part, struct mm_mimeheader **id)
{
	struct mm_mimeheader *header;

	assert(part != NULL);

	if (*id == NULL) {
		header = TAILQ_FIRST(&part->headers);
	} else {
		header = TAILQ_NEXT(*id, next);
	}
	*id = header;

	return header;
}

/** @} */

/** @{
 * @name Accessing and manipulating the MIME part's body
 */

/**
 * Gets the pointer to the MIME part's body data
 *
 * @param part A valid MIME part object
 * @param opaque Whether to get the opaque part or not
 * @return A pointer to the MIME part's body
 * @see mm_mimepart_setbody
 *
 */
char *
mm_mimepart_getbody(struct mm_mimepart *part, int opaque)
{
	assert(part != NULL);

	if (opaque)
		return part->opaque_body;
	else	
		return part->body;
}

/**
 * Sets the MIME part's body data
 *
 * @param part A valid MIME part object
 * @param data A pointer to the data which to set
 * @see mm_mimepart_getbody
 *
 * This functions sets the body data for a given MIME part. The string pointed
 * to by data must be NUL-terminated. The data is copied into the MIME part's
 * body, and thus, the memory pointed to by data can be freed after the
 * operation. 
 */
#if 0
void
mm_mimepart_setbody(struct mm_mimepart *part, const char *data, int opaque)
{
	assert(part != NULL);
	assert(data != NULL);

	if (opaque) {
		part->opaque_body = xstrdup(data);
		part->body = part->opaque_body;
	} else {	
		part->body = xstrdup(data);
	}
	part->length = strlen(data);
}
#endif

/**
 * Gets the length of a given MIME part object
 *
 * @param part A valid MIME part object
 * @returns The size of the part's body in byte.
 *
 * This function returns the total length of the given MIME part's body. The
 * length does not include the headers of the MIME parts. If the function
 * returns 0, no body part is set currently.
 */
size_t
mm_mimepart_getlength(struct mm_mimepart *part)
{
	assert(part != NULL);

	return part->length;
}


/**
 * Decodes a MIME part according to it's encoding using MiniMIME codecs
 *
 * @param A valid MIME part object
 * @return 0 if the MIME part could be successfully decoded or -1 if not
 * @note Sets mm_errno on error
 *
 * This function decodes the body of a MIME part with a registered decoder
 * according to it's Content-Transfer-Encoding header field. 
 */
char *
mm_mimepart_decode(struct mm_mimepart *part)
{
	extern struct mm_codecs codecs;
	struct mm_codec *codec;
	void *decoded;
	
	assert(part != NULL);
	assert(part->type != NULL);

	decoded = NULL;

	/* No encoding associated */
	if (part->type->encstring == NULL)
		return NULL;

	/* Loop through codecs and find a suitable one */
	SLIST_FOREACH(codec, &codecs, next) {
		if (!strcasecmp(part->type->encstring, codec->encoding)) {
			decoded = codec->decoder((char *)part->body);
			break;
		}
	}

	return decoded;
}

/**
 * Creates an ASCII representation of the given MIME part
 *
 * @param part A valid MIME part object
 * @param result Where to store the result
 * @param length Where to store the length of the result
 * @param opaque Whether to use the opaque MIME part
 * @returtn 0 on success or -1 on error.
 * @see mm_context_flatten
 *
 * This function creates an ASCII representation of a given MIME part. It will
 * dynamically allocate the memory needed and stores the result in the memory
 * region pointed to by result. The length of the result will be stored in
 * length. If opaque is set to 1, mm_mimepart_flatten will store an opaque
 * version of the MIME part in result, which means no headers will be created
 * or sanitized. This is particulary useful if the part is digitally signed by
 * e.g. PGP, and the signature spans the header fields of the part in question.
 * 
 */
int
mm_mimepart_flatten(struct mm_mimepart *part, char **result, size_t *length,
    int opaque)
{
	size_t part_length;
	char *buf;
	char *ct_hdr;

	*result = NULL;
	*length = 0;
	buf = NULL;
	ct_hdr = NULL;
	part_length = 0;

	if (opaque && part->opaque_body != NULL) {
		part_length = strlen(part->opaque_body);
		*result = xstrdup(part->opaque_body);
		*length = part_length;
		return(0);
	} else {
		if (part->type == NULL) {
			return(-1);
		}	
		
		ct_hdr = mm_content_tostring(part->type);
		if (ct_hdr == NULL) {
			return(-1);
		}

		part_length += strlen(ct_hdr) + 2;
		part_length += strlen("\r\n") * 2;
		part_length += strlen(part->body);
	
		if (part_length < 0) {
			goto cleanup;
		}	

		buf = (char *) xmalloc(part_length);
		if (buf == NULL) {
			goto cleanup;
		}

		snprintf(buf, part_length, 
		    "%s\r\n\r\n%s\r\n",
		     ct_hdr,
		     part->body);

		xfree(ct_hdr);
		ct_hdr = NULL;

		*result = buf;
		*length = part_length;
	}

	return(0);

cleanup:
	if (ct_hdr != NULL) {
		xfree(ct_hdr);
		ct_hdr = NULL;
	}
	if (buf != NULL) {
		xfree(buf);
		buf = NULL;
	}
	
	*result = NULL;
	*length = 0;
	
	return -1;
}

/**
 * Sets the default Content-Type for a given MIME part
 *
 * @param part A valid MIME part object
 * @param part Whether the Content-Type should be for composite or not
 * @return 0 on success or -1 on failure
 *
 * This function sets a default Content-Type according to RFC 2045 with a value
 * of "text/plain; charset="us-ascii"". This function should only be used if
 * the MIME part in question does not have a valid Content-Type specification.
 */
int
mm_mimepart_setdefaultcontenttype(struct mm_mimepart *part, int composite)
{
	struct mm_content *type;
	struct mm_param *param;

	if (part == NULL) {
		return(-1);
	}

	if (part->type != NULL) {
		mm_content_free(part->type);
		part->type = NULL;
	}

	type = mm_content_new();
	if (composite) {
		type->maintype = xstrdup("multipart");
		type->subtype = xstrdup("mixed");
	} else {
		type->maintype = xstrdup("text");
		type->subtype = xstrdup("plain");
		param = mm_param_new();
		param->name = xstrdup("charset");
		param->value = xstrdup("us-ascii");
		mm_content_attachtypeparam(type, param);
	}	

	mm_mimepart_attachcontenttype(part, type);

	return (0);
}

/** @{ 
 * @name Accessing the MIME part's Content-Type information
 */

/**
 * Attaches a context type object to a MIME part
 *
 * @param part A valid MIME part object
 * @param ct The content type object to attach
 * @return Nothing
 *
 * This function attaches a Content-Type object to a MIME part. It does not
 * care whether the Content-Type suites the actual content in the MIME part,
 * so the programmer should take care of that.
 */
void
mm_mimepart_attachcontenttype(struct mm_mimepart *part, struct mm_content *ct)
{
	part->type = ct;
}

/**
 * Gets the Content-Type of a given MIME part object
 *
 * @param part A valid MIME part object
 * @return The Content-Type object of the specified MIME part
 *
 * This function returns a pointer to the Content-Type object of the given
 * MIME part. This pointer might be set to NULL, indicating that there is
 * no Content-Type object for the given MIME part currently.
 */
struct mm_content *
mm_mimepart_getcontent(struct mm_mimepart *part)
{
	assert(part != NULL);

	return part->type;
}

/** @} */