/* Copyright (c) 2007-2018 Dovecot authors, see the included COPYING file */

#include "lib.h"
#include "array.h"
#include "fdatasync-path.h"
#include "hex-binary.h"
#include "hex-dec.h"
#include "str.h"
#include "istream.h"
#include "istream-crlf.h"
#include "ostream.h"
#include "write-full.h"
#include "index-mail.h"
#include "index-pop3-uidl.h"
#include "mail-copy.h"
#include "dbox-save.h"
#include "mdbox-storage.h"
#include "mdbox-map.h"
#include "mdbox-file.h"
#include "mdbox-sync.h"


struct dbox_save_mail {
	struct dbox_file_append_context *file_append;
	uint32_t seq;
	uint32_t append_offset;
	bool written_to_disk;
};

struct mdbox_save_context {
	struct dbox_save_context ctx;

	struct mdbox_mailbox *mbox;
	struct mdbox_sync_context *sync_ctx;

	struct dbox_file *cur_file;
	struct dbox_file_append_context *cur_file_append;
	struct mdbox_map_append_context *append_ctx;

	ARRAY_TYPE(uint32_t) copy_map_uids;
	struct mdbox_map_atomic_context *atomic;
	struct mdbox_map_transaction_context *map_trans;

	ARRAY(struct dbox_save_mail) mails;
};

static struct dbox_file *
mdbox_copy_file_get_file(struct mailbox_transaction_context *t,
			 uint32_t seq, uoff_t *offset_r)
{
	struct mdbox_save_context *ctx =
		(struct mdbox_save_context *)t->save_ctx;
	const struct mdbox_mail_index_record *rec;
	const void *data;
	uint32_t file_id;

	mail_index_lookup_ext(t->view, seq, ctx->mbox->ext_id, &data, NULL);
	rec = data;

	if (mdbox_map_lookup(ctx->mbox->storage->map, rec->map_uid,
			     &file_id, offset_r) < 0)
		i_unreached();

	return mdbox_file_init(ctx->mbox->storage, file_id);
}

struct dbox_file *
mdbox_save_file_get_file(struct mailbox_transaction_context *t,
			 uint32_t seq, uoff_t *offset_r)
{
	struct mdbox_save_context *ctx =
		(struct mdbox_save_context *)t->save_ctx;
	const struct dbox_save_mail *mails, *mail;
	unsigned int count;

	mails = array_get(&ctx->mails, &count);
	i_assert(count > 0);
	i_assert(seq >= mails[0].seq);

	mail = &mails[seq - mails[0].seq];
	i_assert(mail->seq == seq);

	if (mail->file_append == NULL) {
		/* copied mail */
		return mdbox_copy_file_get_file(t, seq, offset_r);
	}

	/* saved mail */
	i_assert(mail->written_to_disk);
	if (dbox_file_append_flush(mail->file_append) < 0)
		ctx->ctx.failed = TRUE;

	mail->file_append->file->refcount++;
	*offset_r = mail->append_offset;
	return mail->file_append->file;
}

struct mail_save_context *
mdbox_save_alloc(struct mailbox_transaction_context *t)
{
	struct mdbox_mailbox *mbox = (struct mdbox_mailbox *)t->box;
	struct mdbox_save_context *ctx =
		(struct mdbox_save_context *)t->save_ctx;

	i_assert((t->flags & MAILBOX_TRANSACTION_FLAG_EXTERNAL) != 0);

	if (ctx != NULL) {
		/* use the existing allocated structure */
		ctx->cur_file = NULL;
		ctx->ctx.failed = FALSE;
		ctx->ctx.finished = FALSE;
		ctx->ctx.dbox_output = NULL;
		ctx->cur_file_append = NULL;
		return &ctx->ctx.ctx;
	}

	ctx = i_new(struct mdbox_save_context, 1);
	ctx->ctx.ctx.transaction = t;
	ctx->ctx.trans = t->itrans;
	ctx->mbox = mbox;
	ctx->atomic = mdbox_map_atomic_begin(mbox->storage->map);
	ctx->append_ctx = mdbox_map_append_begin(ctx->atomic);
	i_array_init(&ctx->mails, 32);
	t->save_ctx = &ctx->ctx.ctx;
	return t->save_ctx;
}

int mdbox_save_begin(struct mail_save_context *_ctx, struct istream *input)
{
	struct mdbox_save_context *ctx = (struct mdbox_save_context *)_ctx;
	struct dbox_save_mail *save_mail;
	uoff_t mail_size, append_offset;

	/* get the size of the mail to be saved, if possible */
	if (i_stream_get_size(input, TRUE, &mail_size) <= 0) {
		/* we couldn't find out the exact size. fallback to non-exact,
		   maybe it'll give something useful. the mail size is used
		   only to figure out if it's causing mdbox file to grow
		   too large. */
		if (i_stream_get_size(input, FALSE, &mail_size) <= 0)
			mail_size = 0;
	}
	if (mdbox_map_append_next(ctx->append_ctx, mail_size, 0,
				  &ctx->cur_file_append,
				  &ctx->ctx.dbox_output) < 0) {
		ctx->ctx.failed = TRUE;
		return -1;
	}
	i_assert(ctx->ctx.dbox_output->offset <= (uint32_t)-1);
	append_offset = ctx->ctx.dbox_output->offset;

	ctx->cur_file = ctx->cur_file_append->file;
	dbox_save_begin(&ctx->ctx, input);

	save_mail = array_append_space(&ctx->mails);
	save_mail->file_append = ctx->cur_file_append;
	save_mail->seq = ctx->ctx.seq;
	save_mail->append_offset = append_offset;
	return ctx->ctx.failed ? -1 : 0;
}

static int mdbox_save_mail_write_metadata(struct mdbox_save_context *ctx,
					  struct dbox_save_mail *mail)
{
	struct dbox_file *file = mail->file_append->file;
	struct dbox_message_header dbox_msg_hdr;
	uoff_t message_size;
	guid_128_t guid_128;

	i_assert(file->msg_header_size == sizeof(dbox_msg_hdr));

	message_size = ctx->ctx.dbox_output->offset -
		mail->append_offset - mail->file_append->file->msg_header_size;

	dbox_save_write_metadata(&ctx->ctx.ctx, ctx->ctx.dbox_output,
				 message_size, ctx->mbox->box.name, guid_128);
	/* save the 128bit GUID to index so if the map index gets corrupted
	   we can still find the message */
	mail_index_update_ext(ctx->ctx.trans, ctx->ctx.seq,
			      ctx->mbox->guid_ext_id, guid_128, NULL);

	dbox_msg_header_fill(&dbox_msg_hdr, message_size);
	if (o_stream_pwrite(ctx->ctx.dbox_output, &dbox_msg_hdr,
			    sizeof(dbox_msg_hdr), mail->append_offset) < 0) {
		dbox_file_set_syscall_error(file, "pwrite()");
		return -1;
	}
	mail->written_to_disk = TRUE;
	return 0;
}

static int mdbox_save_finish_write(struct mail_save_context *_ctx)
{
	struct mdbox_save_context *ctx = (struct mdbox_save_context *)_ctx;
	struct dbox_save_mail *mail;

	ctx->ctx.finished = TRUE;
	if (ctx->ctx.dbox_output == NULL)
		return -1;

	dbox_save_end(&ctx->ctx);

	mail = array_idx_modifiable(&ctx->mails, array_count(&ctx->mails) - 1);
	if (!ctx->ctx.failed) T_BEGIN {
		if (mdbox_save_mail_write_metadata(ctx, mail) < 0)
			ctx->ctx.failed = TRUE;
		else
			mdbox_map_append_finish(ctx->append_ctx);
	} T_END;

	if (mail->file_append->file->input != NULL) {
		/* if we try to read the saved mail before unlocking file,
		   make sure the input stream doesn't have stale data */
		i_stream_sync(mail->file_append->file->input);
	}
	i_stream_unref(&ctx->ctx.input);

	if (ctx->ctx.failed) {
		index_storage_save_abort_last(&ctx->ctx.ctx, ctx->ctx.seq);
		mdbox_map_append_abort(ctx->append_ctx);
		array_delete(&ctx->mails, array_count(&ctx->mails) - 1, 1);
		return -1;
	}
	return 0;
}

int mdbox_save_finish(struct mail_save_context *ctx)
{
	int ret;

	ret = mdbox_save_finish_write(ctx);
	index_save_context_free(ctx);
	return ret;
}

void mdbox_save_cancel(struct mail_save_context *_ctx)
{
	struct dbox_save_context *ctx = (struct dbox_save_context *)_ctx;

	ctx->failed = TRUE;
	(void)mdbox_save_finish(_ctx);
}

static void
mdbox_save_set_map_uids(struct mdbox_save_context *ctx,
			uint32_t first_map_uid, uint32_t last_map_uid)
{
	struct mdbox_mailbox *mbox = ctx->mbox;
	struct mail_index_view *view = ctx->ctx.ctx.transaction->view;
	const struct mdbox_mail_index_record *old_rec;
	struct mdbox_mail_index_record rec;
	const struct dbox_save_mail *mails;
	unsigned int i, count;
	const void *data;
	uint32_t next_map_uid = first_map_uid;

	mdbox_update_header(mbox, ctx->ctx.trans, NULL);

	i_zero(&rec);
	rec.save_date = ioloop_time;
	mails = array_get(&ctx->mails, &count);
	for (i = 0; i < count; i++) {
		mail_index_lookup_ext(view, mails[i].seq, mbox->ext_id,
				      &data, NULL);
		old_rec = data;
		if (old_rec != NULL && old_rec->map_uid != 0) {
			/* message was copied. keep the existing map uid */
			continue;
		}

		rec.map_uid = next_map_uid++;
		mail_index_update_ext(ctx->ctx.trans, mails[i].seq,
				      mbox->ext_id, &rec, NULL);
	}
	i_assert(next_map_uid == last_map_uid + 1);
}

int mdbox_transaction_save_commit_pre(struct mail_save_context *_ctx)
{
	struct mdbox_save_context *ctx = (struct mdbox_save_context *)_ctx;
	struct mailbox_transaction_context *_t = _ctx->transaction;
	const struct mail_index_header *hdr;
	uint32_t first_map_uid, last_map_uid;

	i_assert(ctx->ctx.finished);

	/* flush/fsync writes to m.* files before locking the map */
	if (mdbox_map_append_flush(ctx->append_ctx) < 0) {
		mdbox_transaction_save_rollback(_ctx);
		return -1;
	}

	/* make sure the map gets locked */
	if (mdbox_map_atomic_lock(ctx->atomic, "saving") < 0) {
		mdbox_transaction_save_rollback(_ctx);
		return -1;
	}
	/* lock the mailbox after map to avoid deadlocks. if we've noticed
	   any corruption, deal with it later, otherwise we won't have
	   up-to-date atomic->sync_view */
	if (mdbox_sync_begin(ctx->mbox, MDBOX_SYNC_FLAG_NO_PURGE |
			     MDBOX_SYNC_FLAG_FORCE |
			     MDBOX_SYNC_FLAG_FSYNC |
			     MDBOX_SYNC_FLAG_NO_REBUILD, ctx->atomic,
			     &ctx->sync_ctx) < 0) {
		mdbox_transaction_save_rollback(_ctx);
		return -1;
	}

	/* assign map UIDs for newly saved messages after we've successfully
	   acquired all the locks. the transaction is now very unlikely to
	   fail. the UIDs are written to the transaction log immediately within
	   this function, but the map is left locked. */
	if (mdbox_map_append_assign_map_uids(ctx->append_ctx, &first_map_uid,
					     &last_map_uid) < 0) {
		mdbox_transaction_save_rollback(_ctx);
		return -1;
	}

	/* update dbox header flags */
	dbox_save_update_header_flags(&ctx->ctx, ctx->sync_ctx->sync_view,
		ctx->mbox->hdr_ext_id, offsetof(struct mdbox_index_header, flags));

	/* assign UIDs for new messages */
	hdr = mail_index_get_header(ctx->sync_ctx->sync_view);
	mail_index_append_finish_uids(ctx->ctx.trans, hdr->next_uid,
				      &_t->changes->saved_uids);

	if (ctx->ctx.highest_pop3_uidl_seq != 0) {
		const struct dbox_save_mail *mails;
		struct seq_range_iter iter;
		unsigned int highest_pop3_uidl_idx;
		uint32_t uid;

		mails = array_idx(&ctx->mails, 0);
		highest_pop3_uidl_idx =
			ctx->ctx.highest_pop3_uidl_seq - mails[0].seq;
		i_assert(mails[highest_pop3_uidl_idx].seq == ctx->ctx.highest_pop3_uidl_seq);

		seq_range_array_iter_init(&iter, &_t->changes->saved_uids);
		if (!seq_range_array_iter_nth(&iter, highest_pop3_uidl_idx, &uid))
			i_unreached();
		index_pop3_uidl_set_max_uid(&ctx->mbox->box, ctx->ctx.trans, uid);
	}

	/* save map UIDs to mailbox index */
	if (first_map_uid != 0)
		mdbox_save_set_map_uids(ctx, first_map_uid, last_map_uid);

	/* increase map's refcount for copied mails */
	if (array_is_created(&ctx->copy_map_uids)) {
		ctx->map_trans = mdbox_map_transaction_begin(ctx->atomic, FALSE);
		if (mdbox_map_update_refcounts(ctx->map_trans,
					       &ctx->copy_map_uids, 1) < 0) {
			mdbox_transaction_save_rollback(_ctx);
			return -1;
		}
		mail_index_sync_set_reason(ctx->sync_ctx->index_sync_ctx, "copying");
	} else {
		mail_index_sync_set_reason(ctx->sync_ctx->index_sync_ctx, "saving");
	}

	_t->changes->uid_validity = hdr->uid_validity;
	return 0;
}

void mdbox_transaction_save_commit_post(struct mail_save_context *_ctx,
					struct mail_index_transaction_commit_result *result)
{
	struct mdbox_save_context *ctx = (struct mdbox_save_context *)_ctx;
	struct mail_storage *storage = _ctx->transaction->box->storage;

	_ctx->transaction = NULL; /* transaction is already freed */

	mail_index_sync_set_commit_result(ctx->sync_ctx->index_sync_ctx,
					  result);

	/* finish writing the mailbox APPENDs */
	if (mdbox_sync_finish(&ctx->sync_ctx, TRUE) == 0) {
		/* commit refcount increases for copied mails */
		if (ctx->map_trans != NULL) {
			if (mdbox_map_transaction_commit(ctx->map_trans, "copy refcount updates") < 0)
				mdbox_map_atomic_set_failed(ctx->atomic);
		}
		/* flush file append writes */
		if (mdbox_map_append_commit(ctx->append_ctx) < 0)
			mdbox_map_atomic_set_failed(ctx->atomic);
	}
	mdbox_map_append_free(&ctx->append_ctx);
	/* update the sync tail offset, everything else
	   was already written at this point. */
	(void)mdbox_map_atomic_finish(&ctx->atomic);

	if (storage->set->parsed_fsync_mode != FSYNC_MODE_NEVER) {
		const char *box_path = mailbox_get_path(&ctx->mbox->box);

		if (fdatasync_path(box_path) < 0) {
			mail_storage_set_critical(storage,
				"fdatasync_path(%s) failed: %m", box_path);
		}
	}
	mdbox_transaction_save_rollback(_ctx);
}

void mdbox_transaction_save_rollback(struct mail_save_context *_ctx)
{
	struct mdbox_save_context *ctx = (struct mdbox_save_context *)_ctx;

	if (!ctx->ctx.finished)
		mdbox_save_cancel(&ctx->ctx.ctx);
	if (ctx->append_ctx != NULL)
		mdbox_map_append_free(&ctx->append_ctx);
	if (ctx->map_trans != NULL)
		mdbox_map_transaction_free(&ctx->map_trans);
	if (ctx->atomic != NULL)
		(void)mdbox_map_atomic_finish(&ctx->atomic);
	if (array_is_created(&ctx->copy_map_uids))
		array_free(&ctx->copy_map_uids);

	if (ctx->sync_ctx != NULL)
		(void)mdbox_sync_finish(&ctx->sync_ctx, FALSE);

	array_free(&ctx->mails);
	i_free(ctx);
}

int mdbox_copy(struct mail_save_context *_ctx, struct mail *mail)
{
	struct mdbox_save_context *ctx = (struct mdbox_save_context *)_ctx;
	struct dbox_save_mail *save_mail;
	struct mdbox_mailbox *src_mbox;
	struct mdbox_mail_index_record rec;
	const void *guid_data;
	guid_128_t wanted_guid;

	ctx->ctx.finished = TRUE;

	if (mail->box->storage != _ctx->transaction->box->storage ||
	    _ctx->transaction->box->disable_reflink_copy_to)
		return mail_storage_copy(_ctx, mail);
	src_mbox = (struct mdbox_mailbox *)mail->box;

	i_zero(&rec);
	rec.save_date = ioloop_time;
	if (mdbox_mail_lookup(src_mbox, mail->transaction->view, mail->seq,
			      &rec.map_uid) < 0) {
		index_save_context_free(_ctx);
		return -1;
	}

	mail_index_lookup_ext(mail->transaction->view, mail->seq,
			      src_mbox->guid_ext_id, &guid_data, NULL);
	if (guid_data == NULL || guid_128_is_empty(guid_data)) {
		/* missing GUID, something's broken. don't copy using
		   refcounting. */
		return mail_storage_copy(_ctx, mail);
	} else if (_ctx->data.guid != NULL &&
		   (guid_128_from_string(_ctx->data.guid, wanted_guid) < 0 ||
		    memcmp(guid_data, wanted_guid, sizeof(wanted_guid)) != 0)) {
		/* GUID change requested. we can't do it with refcount
		   copying */
		return mail_storage_copy(_ctx, mail);
	}

	/* remember the map_uid so we can later increase its refcount */
	if (!array_is_created(&ctx->copy_map_uids))
		i_array_init(&ctx->copy_map_uids, 32);
	array_append(&ctx->copy_map_uids, &rec.map_uid, 1);

	/* add message to mailbox index */
	dbox_save_add_to_index(&ctx->ctx);
	mail_index_update_ext(ctx->ctx.trans, ctx->ctx.seq,
			      ctx->mbox->ext_id, &rec, NULL);

	mail_index_update_ext(ctx->ctx.trans, ctx->ctx.seq,
			      ctx->mbox->guid_ext_id, guid_data, NULL);
	index_copy_cache_fields(_ctx, mail, ctx->ctx.seq);

	save_mail = array_append_space(&ctx->mails);
	save_mail->seq = ctx->ctx.seq;

	mail_set_seq_saving(_ctx->dest_mail, ctx->ctx.seq);
	index_save_context_free(_ctx);
	return 0;
}