/* Copyright (c) 2007-2017 Dovecot authors, see the included COPYING file */

#include "lib.h"
#include "array.h"
#include "llist.h"
#include "str.h"
#include "str-sanitize.h"
#include "imap-util.h"
#include "mail-user.h"
#include "mail-storage-private.h"
#include "notify-plugin.h"
#include "mail-log-plugin.h"


#define MAILBOX_NAME_LOG_LEN 64
#define HEADER_LOG_LEN 80

#define MAIL_LOG_USER_CONTEXT(obj) \
	MODULE_CONTEXT(obj, mail_log_user_module)

enum mail_log_field {
	MAIL_LOG_FIELD_UID	= 0x01,
	MAIL_LOG_FIELD_BOX	= 0x02,
	MAIL_LOG_FIELD_MSGID	= 0x04,
	MAIL_LOG_FIELD_PSIZE	= 0x08,
	MAIL_LOG_FIELD_VSIZE	= 0x10,
	MAIL_LOG_FIELD_FLAGS	= 0x20,
	MAIL_LOG_FIELD_FROM	= 0x40,
	MAIL_LOG_FIELD_SUBJECT	= 0x80
};
#define MAIL_LOG_DEFAULT_FIELDS \
	(MAIL_LOG_FIELD_UID | MAIL_LOG_FIELD_BOX | \
	 MAIL_LOG_FIELD_MSGID | MAIL_LOG_FIELD_PSIZE)

enum mail_log_event {
	MAIL_LOG_EVENT_DELETE		= 0x01,
	MAIL_LOG_EVENT_UNDELETE		= 0x02,
	MAIL_LOG_EVENT_EXPUNGE		= 0x04,
	MAIL_LOG_EVENT_SAVE		= 0x08,
	MAIL_LOG_EVENT_COPY		= 0x10,
	MAIL_LOG_EVENT_MAILBOX_CREATE	= 0x20,
	MAIL_LOG_EVENT_MAILBOX_DELETE	= 0x40,
	MAIL_LOG_EVENT_MAILBOX_RENAME	= 0x80,
	MAIL_LOG_EVENT_FLAG_CHANGE	= 0x100
};
#define MAIL_LOG_DEFAULT_EVENTS \
	(MAIL_LOG_EVENT_DELETE | MAIL_LOG_EVENT_UNDELETE | \
	 MAIL_LOG_EVENT_EXPUNGE | MAIL_LOG_EVENT_SAVE | MAIL_LOG_EVENT_COPY | \
	 MAIL_LOG_EVENT_MAILBOX_DELETE | MAIL_LOG_EVENT_MAILBOX_RENAME)

static const char *field_names[] = {
	"uid",
	"box",
	"msgid",
	"size",
	"vsize",
	"flags",
	"from",
	"subject",
	NULL
};

static const char *event_names[] = {
	"delete",
	"undelete",
	"expunge",
	"save",
	"copy",
	"mailbox_create",
	"mailbox_delete",
	"mailbox_rename",
	"flag_change",
	NULL
};

struct mail_log_user {
	union mail_user_module_context module_ctx;

	enum mail_log_field fields;
	enum mail_log_event events;
	bool cached_only;
};

struct mail_log_message {
	struct mail_log_message *prev, *next;

	enum mail_log_event event;
	bool ignore;
	const char *pretext, *text;
};

struct mail_log_mail_txn_context {
	pool_t pool;
	struct mail_log_message *messages, *messages_tail;
};

static MODULE_CONTEXT_DEFINE_INIT(mail_log_user_module,
				  &mail_user_module_register);

static enum mail_log_field mail_log_field_find(const char *name)
{
	unsigned int i;

	for (i = 0; field_names[i] != NULL; i++) {
		if (strcmp(name, field_names[i]) == 0)
			return 1 << i;
	}
	return 0;
}

static enum mail_log_event mail_log_event_find(const char *name)
{
	unsigned int i;

	if (strcmp(name, "append") == 0) {
		/* v1.x backwards compatibility */
		name = "save";
	}
	for (i = 0; event_names[i] != NULL; i++) {
		if (strcmp(name, event_names[i]) == 0)
			return 1 << i;
	}
	return 0;
}

static enum mail_log_field mail_log_parse_fields(const char *str)
{
	const char *const *tmp;
	static enum mail_log_field field, fields = 0;

	for (tmp = t_strsplit_spaces(str, ", "); *tmp != NULL; tmp++) {
		field = mail_log_field_find(*tmp);
		if (field == 0)
			i_fatal("Unknown field in mail_log_fields: '%s'", *tmp);
		fields |= field;
	}
	return fields;
}

static enum mail_log_event mail_log_parse_events(const char *str)
{
	const char *const *tmp;
	static enum mail_log_event event, events = 0;

	for (tmp = t_strsplit_spaces(str, ", "); *tmp != NULL; tmp++) {
		event = mail_log_event_find(*tmp);
		if (event == 0)
			i_fatal("Unknown event in mail_log_events: '%s'", *tmp);
		events |= event;
	}
	return events;
}

static void mail_log_mail_user_created(struct mail_user *user)
{
	struct mail_log_user *muser;
	const char *str;

	muser = p_new(user->pool, struct mail_log_user, 1);
	MODULE_CONTEXT_SET(user, mail_log_user_module, muser);

	str = mail_user_plugin_getenv(user, "mail_log_fields");
	muser->fields = str == NULL ? MAIL_LOG_DEFAULT_FIELDS :
		mail_log_parse_fields(str);

	str = mail_user_plugin_getenv(user, "mail_log_events");
	muser->events = str == NULL ? MAIL_LOG_DEFAULT_EVENTS :
		mail_log_parse_events(str);

	muser->cached_only =
		mail_user_plugin_getenv(user, "mail_log_cached_only") != NULL;
}

static void mail_log_append_mailbox_name(string_t *str, struct mail *mail)
{
	const char *mailbox_str;

	mailbox_str = mailbox_get_vname(mail->box);
	str_printfa(str, "box=%s",
		    str_sanitize(mailbox_str, MAILBOX_NAME_LOG_LEN));
}

static void
mail_log_append_mail_header(string_t *str, struct mail *mail,
			    const char *name, const char *header)
{
	const char *value;

	if (mail_get_first_header(mail, header, &value) <= 0)
		value = "";
	str_printfa(str, "%s=%s", name, str_sanitize(value, HEADER_LOG_LEN));
}

static void
mail_log_append_uid(struct mail_log_mail_txn_context *ctx,
		    struct mail_log_message *msg, string_t *str, uint32_t uid)
{
	if (uid != 0)
		str_printfa(str, "uid=%u", uid);
	else {
		/* we don't know the uid yet, assign it later */
		str_printfa(str, "uid=");
		msg->pretext = p_strdup(ctx->pool, str_c(str));
		str_truncate(str, 0);
	}
}

static void
mail_log_update_wanted_fields(struct mail *mail, enum mail_log_field fields)
{
	enum mail_fetch_field wanted_fields = 0;
	struct mailbox_header_lookup_ctx *wanted_headers = NULL;
	const char *headers[4];
	unsigned int hdr_idx = 0;

	if ((fields & MAIL_LOG_FIELD_MSGID) != 0)
		headers[hdr_idx++] = "Message-ID";
	if ((fields & MAIL_LOG_FIELD_FROM) != 0)
		headers[hdr_idx++] = "From";
	if ((fields & MAIL_LOG_FIELD_SUBJECT) != 0)
		headers[hdr_idx++] = "Subject";
	if (hdr_idx > 0) {
		i_assert(hdr_idx < N_ELEMENTS(headers));
		headers[hdr_idx] = NULL;
		wanted_headers = mailbox_header_lookup_init(mail->box, headers);
	}

	if ((fields & MAIL_LOG_FIELD_PSIZE) != 0)
		wanted_fields |= MAIL_FETCH_PHYSICAL_SIZE;
	if ((fields & MAIL_LOG_FIELD_VSIZE) != 0)
		wanted_fields |= MAIL_FETCH_VIRTUAL_SIZE;

	mail_add_temp_wanted_fields(mail, wanted_fields, wanted_headers);
	if (wanted_headers != NULL)
		mailbox_header_lookup_unref(&wanted_headers);
}

static void
mail_log_append_mail_message_real(struct mail_log_mail_txn_context *ctx,
				  struct mail *mail, enum mail_log_event event,
				  const char *desc)
{
	struct mail_log_user *muser =
		MAIL_LOG_USER_CONTEXT(mail->box->storage->user);
	struct mail_log_message *msg;
	string_t *text;
	uoff_t size;

	msg = p_new(ctx->pool, struct mail_log_message, 1);

	/* avoid parsing through the message multiple times */
	mail_log_update_wanted_fields(mail, muser->fields);

	text = t_str_new(128);
	str_append(text, desc);
	str_append(text, ": ");
	if ((muser->fields & MAIL_LOG_FIELD_BOX) != 0) {
		mail_log_append_mailbox_name(text, mail);
		str_append(text, ", ");
	}
	if ((muser->fields & MAIL_LOG_FIELD_UID) != 0) {
		if (event != MAIL_LOG_EVENT_SAVE &&
		    event != MAIL_LOG_EVENT_COPY)
			mail_log_append_uid(ctx, msg, text, mail->uid);
		else {
			/* with mbox mail->uid contains the uid, but handle
			   this consistently with all mailbox formats */
			mail_log_append_uid(ctx, msg, text, 0);
		}
		/* make sure UID is assigned to this mail */
		mail->transaction->flags |= MAILBOX_TRANSACTION_FLAG_ASSIGN_UIDS;
		str_append(text, ", ");
	}
	if ((muser->fields & MAIL_LOG_FIELD_MSGID) != 0) {
		mail_log_append_mail_header(text, mail, "msgid", "Message-ID");
		str_append(text, ", ");
	}
	if ((muser->fields & MAIL_LOG_FIELD_PSIZE) != 0) {
		if (mail_get_physical_size(mail, &size) == 0)
			str_printfa(text, "size=%"PRIuUOFF_T, size);
		else
			str_printfa(text, "size=error");
		str_append(text, ", ");
	}
	if ((muser->fields & MAIL_LOG_FIELD_VSIZE) != 0) {
		if (mail_get_virtual_size(mail, &size) == 0)
			str_printfa(text, "vsize=%"PRIuUOFF_T, size);
		else
			str_printfa(text, "vsize=error");
		str_append(text, ", ");
	}
	if ((muser->fields & MAIL_LOG_FIELD_FROM) != 0) {
		mail_log_append_mail_header(text, mail, "from", "From");
		str_append(text, ", ");
	}
	if ((muser->fields & MAIL_LOG_FIELD_SUBJECT) != 0) {
		mail_log_append_mail_header(text, mail, "subject", "Subject");
		str_append(text, ", ");
	}
	if ((muser->fields & MAIL_LOG_FIELD_FLAGS) != 0) {
		str_printfa(text, "flags=(");
		imap_write_flags(text, mail_get_flags(mail),
				 mail_get_keywords(mail));
		str_append(text, "), ");
	}
	str_truncate(text, str_len(text)-2);

	msg->event = event;
	msg->text = p_strdup(ctx->pool, str_c(text));
	DLLIST2_APPEND(&ctx->messages, &ctx->messages_tail, msg);
}

static void mail_log_add_dummy_msg(struct mail_log_mail_txn_context *ctx,
				   enum mail_log_event event)
{
	struct mail_log_message *msg;

	msg = p_new(ctx->pool, struct mail_log_message, 1);
	msg->event = event;
	msg->ignore = TRUE;
	DLLIST2_APPEND(&ctx->messages, &ctx->messages_tail, msg);
}

static void
mail_log_append_mail_message(struct mail_log_mail_txn_context *ctx,
			     struct mail *mail, enum mail_log_event event,
			     const char *desc)
{
	struct mail_log_user *muser =
		MAIL_LOG_USER_CONTEXT(mail->box->storage->user);

	if ((muser->events & event) == 0) {
		if (event == MAIL_LOG_EVENT_SAVE ||
		    event == MAIL_LOG_EVENT_COPY)
			mail_log_add_dummy_msg(ctx, event);
		return;
	}

	T_BEGIN {
		enum mail_lookup_abort orig_lookup_abort = mail->lookup_abort;

		if (event != MAIL_LOG_EVENT_SAVE && muser->cached_only)
			mail->lookup_abort = MAIL_LOOKUP_ABORT_NOT_IN_CACHE;
		mail_log_append_mail_message_real(ctx, mail, event, desc);
		mail->lookup_abort = orig_lookup_abort;
	} T_END;
}

static void *
mail_log_mail_transaction_begin(struct mailbox_transaction_context *t ATTR_UNUSED)
{
	pool_t pool;
	struct mail_log_mail_txn_context *ctx;

	pool = pool_alloconly_create("mail-log", 2048);
	ctx = p_new(pool, struct mail_log_mail_txn_context, 1);
	ctx->pool = pool;
	return ctx;
}

static void mail_log_mail_save(void *txn, struct mail *mail)
{
	struct mail_log_mail_txn_context *ctx =
		(struct mail_log_mail_txn_context *)txn;

	mail_log_append_mail_message(ctx, mail, MAIL_LOG_EVENT_SAVE, "save");
}

static void mail_log_mail_copy(void *txn, struct mail *src, struct mail *dst)
{
	struct mail_log_mail_txn_context *ctx =
		(struct mail_log_mail_txn_context *)txn;
	struct mail_private *src_pmail = (struct mail_private *)src;
	struct mailbox *src_box = src->box;
	const char *desc;

	if (src_pmail->vmail != NULL) {
		/* copying a mail from virtual storage. src points to the
		   backend mail, but we want to log the virtual mailbox name. */
		src_box = src_pmail->vmail->box;
	}
	desc = t_strdup_printf("copy from %s",
			       str_sanitize(mailbox_get_vname(src_box),
					    MAILBOX_NAME_LOG_LEN));
	mail_log_append_mail_message(ctx, dst,
				     MAIL_LOG_EVENT_COPY, desc);
}

static void mail_log_mail_expunge(void *txn, struct mail *mail)
{
	struct mail_log_mail_txn_context *ctx =
		(struct mail_log_mail_txn_context *)txn;
	
	mail_log_append_mail_message(ctx, mail, MAIL_LOG_EVENT_EXPUNGE,
				     "expunge");
}

static void mail_log_mail_update_flags(void *txn, struct mail *mail,
				       enum mail_flags old_flags)
{
	struct mail_log_mail_txn_context *ctx =
		(struct mail_log_mail_txn_context *)txn;
	enum mail_flags new_flags = mail_get_flags(mail);

	if (((old_flags ^ new_flags) & MAIL_DELETED) == 0) {
		mail_log_append_mail_message(ctx, mail,
					     MAIL_LOG_EVENT_FLAG_CHANGE,
					     "flag_change");
	} else if ((old_flags & MAIL_DELETED) == 0) {
		mail_log_append_mail_message(ctx, mail, MAIL_LOG_EVENT_DELETE,
					     "delete");
	} else {
		mail_log_append_mail_message(ctx, mail, MAIL_LOG_EVENT_UNDELETE,
					     "undelete");
	}
}

static void
mail_log_mail_update_keywords(void *txn, struct mail *mail, 
			      const char *const *old_keywords ATTR_UNUSED)
{
	struct mail_log_mail_txn_context *ctx =
		(struct mail_log_mail_txn_context *)txn;

	mail_log_append_mail_message(ctx, mail, MAIL_LOG_EVENT_FLAG_CHANGE,
				     "flag_change");
}

static void mail_log_save(const struct mail_log_message *msg, uint32_t uid)
{
	if (msg->ignore) {
		/* not logging this save/copy */
	} else if (msg->pretext == NULL)
		i_info("%s", msg->text);
	else if (uid != 0)
		i_info("%s%u%s", msg->pretext, uid, msg->text);
	else
		i_info("%serror%s", msg->pretext, msg->text);
}

static void
mail_log_mail_transaction_commit(void *txn,
				 struct mail_transaction_commit_changes *changes)
{
	struct mail_log_mail_txn_context *ctx =
		(struct mail_log_mail_txn_context *)txn;
	struct mail_log_message *msg;
	struct seq_range_iter iter;
	unsigned int n = 0;
	uint32_t uid;

	seq_range_array_iter_init(&iter, &changes->saved_uids);
	for (msg = ctx->messages; msg != NULL; msg = msg->next) {
		if (msg->event == MAIL_LOG_EVENT_SAVE ||
		    msg->event == MAIL_LOG_EVENT_COPY) {
			if (!seq_range_array_iter_nth(&iter, n++, &uid))
				uid = 0;
			mail_log_save(msg, uid);
		} else {
			i_assert(msg->pretext == NULL);
			i_info("%s", msg->text);
		}
	}
	i_assert(!seq_range_array_iter_nth(&iter, n, &uid));

	pool_unref(&ctx->pool);
}

static void mail_log_mail_transaction_rollback(void *txn)
{
	struct mail_log_mail_txn_context *ctx =
		(struct mail_log_mail_txn_context *)txn;

	pool_unref(&ctx->pool);
}

static void
mail_log_mailbox_create(struct mailbox *box)
{
	struct mail_log_user *muser = MAIL_LOG_USER_CONTEXT(box->storage->user);

	if ((muser->events & MAIL_LOG_EVENT_MAILBOX_CREATE) == 0)
		return;

	i_info("Mailbox created: %s",
	       str_sanitize(mailbox_get_vname(box), MAILBOX_NAME_LOG_LEN));
}

static void
mail_log_mailbox_delete_commit(void *txn ATTR_UNUSED, struct mailbox *box)
{
	struct mail_log_user *muser = MAIL_LOG_USER_CONTEXT(box->storage->user);

	if ((muser->events & MAIL_LOG_EVENT_MAILBOX_DELETE) == 0)
		return;

	i_info("Mailbox deleted: %s",
	       str_sanitize(mailbox_get_vname(box), MAILBOX_NAME_LOG_LEN));
}

static void
mail_log_mailbox_rename(struct mailbox *src, struct mailbox *dest)
{
	struct mail_log_user *muser = MAIL_LOG_USER_CONTEXT(src->storage->user);

	if ((muser->events & MAIL_LOG_EVENT_MAILBOX_RENAME) == 0)
		return;

	i_info("Mailbox renamed: %s -> %s",
	       str_sanitize(mailbox_get_vname(src), MAILBOX_NAME_LOG_LEN),
	       str_sanitize(mailbox_get_vname(dest), MAILBOX_NAME_LOG_LEN));
}

static const struct notify_vfuncs mail_log_vfuncs = {
	.mail_transaction_begin = mail_log_mail_transaction_begin,
	.mail_save = mail_log_mail_save,
	.mail_copy = mail_log_mail_copy,
	.mail_expunge = mail_log_mail_expunge,
	.mail_update_flags = mail_log_mail_update_flags,
	.mail_update_keywords = mail_log_mail_update_keywords,
	.mail_transaction_commit = mail_log_mail_transaction_commit,
	.mail_transaction_rollback = mail_log_mail_transaction_rollback,
	.mailbox_create = mail_log_mailbox_create,
	.mailbox_delete_commit = mail_log_mailbox_delete_commit,
	.mailbox_rename = mail_log_mailbox_rename
};

static struct notify_context *mail_log_ctx;

static struct mail_storage_hooks mail_log_mail_storage_hooks = {
	.mail_user_created = mail_log_mail_user_created
};

void mail_log_plugin_init(struct module *module)
{
	mail_log_ctx = notify_register(&mail_log_vfuncs);
	mail_storage_hooks_add(module, &mail_log_mail_storage_hooks);
}

void mail_log_plugin_deinit(void)
{
	mail_storage_hooks_remove(&mail_log_mail_storage_hooks);
	notify_unregister(mail_log_ctx);
}

const char *mail_log_plugin_dependencies[] = { "notify", NULL };