#!/usr/bin/python
import argparse
import datetime
import os
import sqlite3

import boto3
import botocore
import humanize
import psycopg2
import tqdm
import yaml
import sys

# Schema for our sqlite database cache
SCHEMA = """
    CREATE TABLE IF NOT EXISTS media (
        origin TEXT NOT NULL,  -- empty string if local media
        media_id TEXT NOT NULL,
        filesystem_id TEXT NOT NULL,
        -- Type is "local" or "remote"
        type TEXT NOT NULL,
        known_deleted BOOLEAN NOT NULL
    );

    CREATE UNIQUE INDEX IF NOT EXISTS media_id_idx ON media(origin, media_id);
    CREATE INDEX IF NOT EXISTS deleted_idx ON media(known_deleted);
"""

progress = True

def parse_duration(string):
    """Parse a string into a duration supports suffix of d, m or y.
    """
    suffix = string[-1]
    number = string[:-1]

    try:
        number = int(number)
    except ValueError:
        raise argparse.ArgumentTypeError(
            "duration must be an integer followed by a 'd', 'm' or 'y' suffix"
        )

    now = datetime.datetime.now()
    if suffix == "d":
        then = now - datetime.timedelta(days=number)
    elif suffix == "m":
        then = now - datetime.timedelta(days=30 * number)
    elif suffix == "y":
        then = now - datetime.timedelta(days=365 * number)
    else:
        raise argparse.ArgumentTypeError(
            "duration must end in 'd', 'm' or 'y'"
        )

    return then


def run_update_db(postgres_conn, sqlite_conn, before_date):
    """Entry point for update-db command
    """

    local_sql = """
        SELECT '', media_id, media_id
        FROM local_media_repository
        WHERE
            COALESCE(last_access_ts, created_ts) < %s
            AND url_cache IS NULL
    """

    remote_sql = """
        SELECT media_origin, media_id, filesystem_id
        FROM remote_media_cache
        WHERE
            COALESCE(last_access_ts, created_ts) < %s
    """

    last_access_ts = int(before_date.timestamp() * 1000)

    print(
        "Syncing files that haven't been accessed since:",
        before_date.isoformat(" "),
    )

    update_count = 0
    with sqlite_conn:
        sqlite_cur = sqlite_conn.cursor()
        with postgres_conn.cursor() as pg_curs:
            for sql, mtype in ((local_sql, "local"), (remote_sql, "remote")):
                pg_curs.execute(sql, (last_access_ts,))

                for (origin, media_id, filesystem_id) in pg_curs:
                    sqlite_cur.execute(
                        """
                        INSERT OR IGNORE INTO media
                        (origin, media_id, filesystem_id, type, known_deleted)
                        VALUES (?, ?, ?, ?, ?)
                    """,
                        (origin, media_id, filesystem_id, mtype, False),
                    )
                    update_count += sqlite_cur.rowcount

    print("Synced", update_count, "new rows")

    postgres_conn.close()


def run_check_delete(sqlite_conn, base_path):
    """Entry point for check-deleted command
    """
    deleted = []
    if progress:
        it = tqdm.tqdm(
                get_not_deleted(sqlite_conn),
                unit="files",
                total=get_not_deleted_count(sqlite_conn)
        )
    else:
        it = get_not_deleted(sqlite_conn)
        print("Checking on ", get_not_deleted_count(sqlite_conn), " undeleted files")

    for origin, media_id, filesystem_id, m_type in it:
        if m_type == "local":
            file_path = os.path.join(
                base_path,
                "local_content",
                filesystem_id[:2],
                filesystem_id[2:4],
                filesystem_id[4:],
            )
        elif m_type == "remote":
            file_path = os.path.join(
                base_path,
                "remote_content",
                origin,
                filesystem_id[:2],
                filesystem_id[2:4],
                filesystem_id[4:],
            )
        else:
            raise Exception("Unexpected media type %r", m_type)

        if not os.path.exists(file_path):
            deleted.append((origin, media_id))

    with sqlite_conn:
        sqlite_conn.executemany(
            """
            UPDATE media SET known_deleted = ?
            WHERE origin = ? AND media_id = ?
            """,
            ((True, o, m) for o, m in deleted),
        )

    print("Updated", len(deleted), "as deleted")


def mark_as_deleted(sqlite_conn, origin, media_id):
    with sqlite_conn:
        sqlite_conn.execute(
            """
            UPDATE media SET known_deleted = ?
            WHERE origin = ? AND media_id = ?
        """,
            (True, origin, media_id),
        )


def get_not_deleted_count(sqlite_conn):
    """Get count of all rows in our cache that we don't think have been deleted
    """
    cur = sqlite_conn.cursor()

    cur.execute(
        """
        SELECT COALESCE(count(*), 0) FROM media
        WHERE NOT known_deleted
    """
    )
    count, = cur.fetchone()
    return count


def get_not_deleted(sqlite_conn):
    """Get all rows in our cache that we don't think have been deleted
    """
    cur = sqlite_conn.cursor()

    cur.execute(
        """
        SELECT origin, media_id, filesystem_id, type FROM media
        WHERE NOT known_deleted
    """
    )
    return cur


def to_path(origin, filesystem_id, m_type):
    """Get a relative path to the given media
    """
    if m_type == "local":
        file_path = os.path.join(
            "local_content",
            filesystem_id[:2],
            filesystem_id[2:4],
            filesystem_id[4:],
        )
    elif m_type == "remote":
        file_path = os.path.join(
            "remote_content",
            origin,
            filesystem_id[:2],
            filesystem_id[2:4],
            filesystem_id[4:],
        )
    else:
        raise Exception("Unexpected media type %r", m_type)

    return file_path


def check_file_in_s3(s3, bucket, key):
    """Check the file exists in S3 (though it could be different)
    """
    try:
        s3.head_object(Bucket=bucket, Key=key)
    except botocore.exceptions.ClientError as e:
        if int(e.response["Error"]["Code"]) == 404:
            return False
        raise

    return True


def run_write(sqlite_conn, output_file):
    """Entry point for write command
    """
    for origin, _, filesystem_id, m_type in get_not_deleted(sqlite_conn):
        file_path = to_path(origin, filesystem_id, m_type)
        print(file_path, file=output_file)


def run_upload(
    s3, bucket, sqlite_conn, base_path, should_delete, storage_class
):
    """Entry point for upload command
    """
    total = get_not_deleted_count(sqlite_conn)

    uploaded = 0
    uploaded_bytes = 0
    deleted = 0
    deleted_bytes = 0

    # This is a progress bar
    if progress:
        it = tqdm.tqdm(get_not_deleted(sqlite_conn), unit="files", total=total)
    else:
        print("Uploading ", total, " files")
        it = get_not_deleted(sqlite_conn)

    for origin, media_id, filesystem_id, m_type in it:
        rel_file_path = to_path(origin, filesystem_id, m_type)

        local_path = os.path.join(base_path, rel_file_path)
        path_exists = os.path.exists(local_path)
        if not path_exists:
            mark_as_deleted(sqlite_conn, origin, media_id)
            continue

        if not check_file_in_s3(s3, bucket, rel_file_path):
            try:
                s3.upload_file(
                    local_path,
                    bucket,
                    rel_file_path,
                    ExtraArgs={"StorageClass": storage_class},
                )
            except Exception as e:
                print("Failed to upload file %s: %s", local_path, e)
                continue

            uploaded += 1
            uploaded_bytes += os.path.getsize(local_path)

        if should_delete:
            size = os.path.getsize(local_path)
            os.remove(local_path)

            try:
                # This may have lead to an empty directory, so lets remove all
                # that are empty
                os.removedirs(os.path.dirname(local_path))
            except Exception:
                # The directory might not be empty, or maybe we don't have
                # permission. Either way doesn't really matter.
                pass

            mark_as_deleted(sqlite_conn, origin, media_id)

            deleted += 1
            deleted_bytes += size

    print("Uploaded", uploaded, "files out of", total)
    print("Uploaded", humanize.naturalsize(uploaded_bytes, gnu=True))
    print("Deleted", deleted, "files")
    print("Deleted", humanize.naturalsize(deleted_bytes, gnu=True))


def get_sqlite_conn(parser):
    """Attempt to get a sqlite connection to cache.db, or exit.
    """
    try:
        sqlite_conn = sqlite3.connect("cache.db")
        sqlite_conn.executescript(SCHEMA)
    except sqlite3.Error as e:
        parser.error("Could not open 'cache.db' as sqlite DB: %s" % (e,))

    return sqlite_conn


def get_postgres_conn(parser):
    """Attempt to get a postgres connection based on database.yaml, or exit.
    """
    try:
        database_yaml = yaml.safe_load(open("database.yaml"))
    except FileNotFoundError:
        parser.error("Could not find database.yaml")
    except yaml.YAMLError as e:
        parser.error("database.yaml is not valid yaml: %s" % (e,))

    try:
        postgres_conn = psycopg2.connect(**database_yaml)
    except psycopg2.Error as e:
        parser.error("Could not connect to postgres database: %s" % (e,))

    return postgres_conn


def main():
    parser = argparse.ArgumentParser(prog="s3_media_upload")
    parser.add_argument("--no-progress", help="do not show progress bars", action="store_true", dest="no_progress")
    subparsers = parser.add_subparsers(help="command to run", dest="cmd")

    update_db_parser = subparsers.add_parser(
        "update-db", help="Syncs rows from database to local cache"
    )
    update_db_parser.add_argument(
        "duration",
        type=parse_duration,
        help="Fetch rows that haven't been accessed in the duration given,"
        " accepts duration of the form of e.g. 1m (one month). Valid suffixes"
        " are d, m or y. NOTE: Currently does not remove entries from the cache",
    )

    deleted_parser = subparsers.add_parser(
        "check-deleted",
        help="Check whether files in the local cache still exist under given"
        " path",
    )
    deleted_parser.add_argument(
        "base_path", help="Base path of the media store directory"
    )

    update_parser = subparsers.add_parser(
        "update",
        help="Updates local cache. Equivalent to running update-db and"
        " check-deleted",
    )
    update_parser.add_argument(
        "base_path", help="Base path of the media store directory"
    )
    update_parser.add_argument(
        "duration",
        type=parse_duration,
        help="Fetch rows that haven't been accessed in the duration given,"
        " accepts duration of the form of e.g. 1m (one month). Valid suffixes"
        " are d, m or y. NOTE: Currently does not remove entries from the cache",
    )

    write_parser = subparsers.add_parser(
        "write",
        help="Outputs all files in local cache that we may not have deleted,"
        " check-deleted should be run first to update cache.",
    )
    write_parser.add_argument(
        "out",
        type=argparse.FileType("w", encoding="UTF-8"),
        default="-",
        nargs="?",
        help="File to output list to, or '-' for stdout",
    )

    upload_parser = subparsers.add_parser(
        "upload", help="Uploads media to s3 based on local cache"
    )
    upload_parser.add_argument(
        "base_path", help="Base path of the media store directory"
    )
    upload_parser.add_argument("bucket", help="S3 bucket to upload to")
    upload_parser.add_argument(
        "--storage-class",
        help="S3 storage class to use",
        nargs="?",
        choices=[
            "STANDARD",
            "REDUCED_REDUNDANCY",
            "STANDARD_IA",
            "ONEZONE_IA",
        ],
        default="STANDARD",
    )

    upload_parser.add_argument(
        "--delete",
        action="store_const",
        const=True,
        help="Deletes local copy from media store on succesful upload",
    )

    upload_parser.add_argument(
        "--endpoint-url",
        help="S3 endpoint url to use",
        default=None
    )

    args = parser.parse_args()
    if args.no_progress:
        global progress
        progress = False

    if args.cmd == "write":
        sqlite_conn = get_sqlite_conn(parser)
        run_write(sqlite_conn, args.out)
        return

    if args.cmd == "update-db":
        sqlite_conn = get_sqlite_conn(parser)
        postgres_conn = get_postgres_conn(parser)
        run_update_db(postgres_conn, sqlite_conn, args.duration)
        return

    if args.cmd == "check-deleted":
        sqlite_conn = get_sqlite_conn(parser)
        run_check_delete(sqlite_conn, args.base_path)
        return

    if args.cmd == "update":
        sqlite_conn = get_sqlite_conn(parser)
        postgres_conn = get_postgres_conn(parser)
        run_update_db(postgres_conn, sqlite_conn, args.duration)
        run_check_delete(sqlite_conn, args.base_path)
        return

    if args.cmd == "upload":
        sqlite_conn = get_sqlite_conn(parser)
        s3 = boto3.client("s3", endpoint_url=args.endpoint_url)
        run_upload(
            s3,
            args.bucket,
            sqlite_conn,
            args.base_path,
            should_delete=args.delete,
            storage_class=args.storage_class,
        )
        return

    parser.error("Valid subcommand must be specified")


if __name__ == "__main__":
    main()