//
// JobScheduleDescription.cs
//
// Author:
//       Carsten Sonne Larsen <cs@innolan.dk>
//
// Copyright (c) 2013 Carsten Sonne Larsen
//
// Permission is hereby granted, free of charge, to any person obtaining a copy
// of this software and associated documentation files (the "Software"), to deal
// in the Software without restriction, including without limitation the rights
// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
// copies of the Software, and to permit persons to whom the Software is
// furnished to do so, subject to the following conditions:
//
// The above copyright notice and this permission notice shall be included in
// all copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
// THE SOFTWARE.
using System;

namespace Ntp.Process
{
    /// <summary>
    /// A description of job schedule rules.
    /// </summary>
    public sealed class JobScheduleDescription
    {
        /// <summary>
        /// Initializes a new instance of the <see cref="Ntp.Process.JobScheduleDescription"/> class.
        /// </summary>
        /// <param name="initialRun">If set to <c>true</c> initial run.</param>
        /// <param name="fixedRun">If set to <c>true</c> fixed run.</param>
        /// <param name="frequency">Frequency in minutes.</param>
        public JobScheduleDescription (bool initialRun, bool fixedRun, int frequency)
        {
            this.initialRun = initialRun || (frequency == 0);
            this.fixedRun = fixedRun;
            this.frequency = frequency;
            initialRunDone = false;
        }

        private readonly bool initialRun;
        private readonly bool fixedRun;
        private readonly int frequency;
        private bool initialRunDone;

        /// <summary>
        /// Gets a value indicating whether this <see cref="Ntp.Process.JobScheduleDescription"/>
        /// should do an initial run upon first call.
        /// </summary>
        /// <value><c>true</c> if initial run; otherwise, <c>false</c>.</value>
        public bool InitialRun {
            get { return initialRun; }
        }

        /// <summary>
        /// Gets a value indicating whether this <see cref="Ntp.Process.JobScheduleDescription"/> has
        /// a fixed schedule frequence, eg. cannot be moved.
        /// </summary>
        /// <value><c>true</c> if fixed run; otherwise, <c>false</c>.</value>
        public bool FixedRun {
            get { return fixedRun; }
        }

        /// <summary>
        /// Gets the schedule frequency in minutes.
        /// </summary>
        /// <value>The frequency.</value>
        public int Frequency {
            get { return frequency; }
        }

        /// <summary>
        /// Gets a value indicating whether this description allow schedules to be moved.
        /// </summary>
        /// <value><c>true</c> if this instance can move; otherwise, <c>false</c>.</value>
        public bool CanMove {
            get { return !(initialRun && !initialRunDone) && !fixedRun; }
        }

        /// <summary>
        /// Creates a new scheduled job based on description and parameters.
        /// </summary>
        /// <returns>The new.</returns>
        /// <param name="job">Job.</param>
        /// <param name="start">Start.</param>
        /// <param name="offset">Offset.</param>
        public ScheduledJob CreateNew (Job job, DateTime start, double offset)
        {
            if (initialRun && !initialRunDone) {
                initialRunDone = true;
                return new ScheduledJob (job, start);
            }

            return new ScheduledJob (job, CalculateNextRun (start).AddMinutes (offset));
        }

        /// <summary>
        /// Creates a postponed job schedule.
        /// </summary>
        /// <returns>The postponed.</returns>
        /// <param name="job">Job.</param>
        public ScheduledJob CreatePostponed (Job job)
        {
            double offset = frequency / 100;

            if (offset > 2) {
                offset = 2;
            } else if (offset < 0.5) {
                offset = 0.5;
            }

            return new ScheduledJob (job, DateTime.Now.AddMinutes (offset));
        }

        /// <summary>
        /// Calculates the time of next run according to description parameters.
        /// </summary>
        /// <returns>The next run.</returns>
        /// <param name="start">Start.</param>
        public DateTime CalculateNextRun (DateTime start)
        {
            if (frequency == -1)
                return DateTime.MaxValue;
            else if (frequency == 0 || (initialRun && !initialRunDone))
                return start;

            int multiplier = Convert.ToInt32 (System.Math.Truncate ((double)(start.Hour * 60 + start.Minute) / frequency));
            int startMinuttes = multiplier * frequency;

            int hour = (startMinuttes + frequency) / 60;
            int minute = (startMinuttes + frequency) % 60;

            if (hour >= 24) {
                hour -= 24;
                start = start.AddDays (1);
            }

            if (minute >= 60) {
                minute -= 60;
                start = start.AddHours (1);
            }

            DateTime next = new DateTime (start.Year, start.Month, start.Day, hour, minute, 0);

            return next;
        }
    }
}