/* mailstore.c - mail storage backends
 *
 * Copyright © 2009 Carl Worth
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see http://www.gnu.org/licenses/ .
 */

#include <stdio.h>
#include <stdarg.h>
#include <couchdb-session.h>
#include <couchdb-database.h>
#include <couchdb-document.h>
#include <glib.h>

#include "notmuch-private.h"

typedef struct _notmuch_mailstore {
    notmuch_status_t (*constructor) (void **data, va_list args);
    FILE *(*open) (struct _notmuch_mailstore *mailstore, const char *filename);
    int (*close) (struct _notmuch_mailstore *mailstore, FILE *);
    int (*rename) (struct _notmuch_mailstore *mailstore, const char *old_filename,
		   const char *new_filename);
    void *data;
} _notmuch_mailstore;

static notmuch_status_t
_maildir_constructor (void **data, unused (va_list ap))
{
    (*data) = NULL;
    return NOTMUCH_STATUS_SUCCESS;
}

static FILE *
_maildir_open_function (unused (notmuch_mailstore_t *mailstore),
			const char *filename)
{
    return fopen (filename, "r");
}

static int
_maildir_close_function (unused (notmuch_mailstore_t *mailstore),
			 FILE *file)
{
    return fclose (file);
}

static int
_maildir_rename_function (unused (notmuch_mailstore_t *mailstore),
			  const char *old_filename, const char *new_filename)
{
    return rename (old_filename, new_filename);
}

struct _couchdb_data {
    char *db_path;
    CouchdbDatabase *database;
    GHashTable *files_to_documents;
};

/* CouchDB mailstore */
static notmuch_status_t
_couchdb_constructor (void **data, va_list ap)
{
    CouchdbSession *session = NULL;
    CouchdbDatabase *database = NULL;
    GError *error = NULL;
    char *uri = NULL;
    char *db_name = NULL;
    struct _couchdb_data *my_data = NULL;

    uri = va_arg (ap, char*);
    session = couchdb_session_new (uri);

    db_name = va_arg (ap, char*);
    database = couchdb_session_get_database (session, db_name, &error);
    if (database == NULL) {
	fprintf (stderr, "Couldn't access database %s: %s\n", db_name,
		 error->message);
	return NOTMUCH_STATUS_FILE_ERROR;
    }

    my_data = talloc_size (NULL, sizeof (struct _couchdb_data));
    my_data->database = database;
    my_data->db_path  = va_arg (ap, char*);
    my_data->files_to_documents = g_hash_table_new (NULL, NULL);
    (*data) = (void*)my_data;

    return NOTMUCH_STATUS_SUCCESS;
}

static FILE *
_couchdb_open_function (notmuch_mailstore_t *mailstore,
			const char *filename)
{
    CouchdbDatabase *database = NULL;
    CouchdbDocument *document = NULL;
    GError *error = NULL;
    const char *text = NULL;
    const char *relative = NULL;
    struct _couchdb_data *data = (struct _couchdb_data *)mailstore->data;
    FILE *ret = NULL;
    database = data->database;
    /* message assumes all files should be contained within db_path.
     * This isn't true for us, so remove the db_path.
     * I'd like to use _notmuch_database_relative_path but I don't have
     * a notmuch_database_t*.
     */
    relative = filename;
    if (strncmp (filename, data->db_path, strlen (data->db_path)) == 0) {
	relative = filename + strlen (data->db_path);
	while (*relative == '/' && *(relative+1) == '/')
	    relative++;
    }

    document = couchdb_database_get_document (database, relative, &error);
    if (document == NULL)
	/* file doesn't exist. Maybe it got deleted? */
	return NULL;

    text = couchdb_document_get_string_field (document, "text");
    /* FIXME: null bytes in the mail file? */
    ret = fmemopen ((char *)text, strlen(text), "r");
    g_hash_table_insert (data->files_to_documents, ret, document);
    return ret;
}

static int
_couchdb_close_function (notmuch_mailstore_t *mailstore, FILE *file)
{
    struct _couchdb_data *data = (struct _couchdb_data *)mailstore->data;
    GHashTable *hash = data->files_to_documents;
    CouchdbDocument *document;
    document = g_hash_table_lookup (hash, file);
    g_object_unref (document);
    fclose (file); /* just to be polite ;) */
    g_hash_table_remove (hash, file);
    return 0;
}

static int
_couchdb_rename_function (unused (notmuch_mailstore_t *mailstore),
			  unused (const char *old_filename),
			  unused (const char *new_filename))
{
    /* Pass for now. */
    return 0;
}

/* A mailstore is defined as:
 *
 * - A function used to "open" a mail message. This takes the
 *   "filename" for the file and should return a FILE *.
 *
 * - A function to "rename" a mail message, which is currently only
 *   used in tags_to_maildir_flags.
 *
 * - A "constructor" that creates a mailstore object of the requisite
 *   type. Arguments are passed via va_args.
 *
 * A mailstore also has a "data" field that can be used to store
 * instance-specific information about this mailstore -- for example,
 * a CouchDB URL or a path. FIXME: mailstores are all statically
 * allocated, so maybe we shouldn't do this.
 */
_notmuch_mailstore
notmuch_mailstore_maildir = { _maildir_constructor,
			      _maildir_open_function, _maildir_close_function,
			      _maildir_rename_function,
			      NULL };

_notmuch_mailstore
notmuch_mailstore_couchdb = { _couchdb_constructor,
			      _couchdb_open_function, _couchdb_close_function,
			      _couchdb_rename_function,
			      NULL};


_notmuch_mailstore *
notmuch_mailstore_get_by_name (const char *name)
{
    if (strcmp (name, "maildir") == 0)
	return &notmuch_mailstore_maildir;

    if (strcmp (name, "couchdb") == 0)
	return &notmuch_mailstore_couchdb;

    return NULL;
}

FILE *
notmuch_mailstore_open (notmuch_mailstore_t *mailstore, const char *filename)
{
    return mailstore->open (mailstore, filename);
}

int
notmuch_mailstore_rename (notmuch_mailstore_t *mailstore, const char *old_filename,
			  const char *new_filename)
{
    return mailstore->rename (mailstore, old_filename, new_filename);
}

int
notmuch_mailstore_close (notmuch_mailstore_t *mailstore, FILE *file)
{
    return mailstore->close (mailstore, file);
}

notmuch_status_t
notmuch_mailstore_construct (notmuch_mailstore_t *mailstore, ...)
{
    va_list va_args;
    notmuch_status_t status;

    va_start (va_args, mailstore);

    status = mailstore->constructor (&mailstore->data, va_args);

    va_end (va_args);
    return status;
}