Previewing Changes#

using Plen;

static Moment Day(int day) =>
    Moment.FromYmdHm(2026, 1, day, 0, 0) ?? throw new InvalidOperationException("invalid date");

var data = new ProjectData
{
    Tasks =
    [
        new TaskData("a") { StartDate = Day(1), Duration = 2.0 },
        new TaskData("b") { StartDate = Day(1), Duration = 1.0 },
    ],
    Links = [new LinkData { Id = "ab", Source = "a", Target = "b" }],
};
// All time is working time: plain day arithmetic, no weekends.
data.Config.UseCalendars = false;

var project = new Project();
var options = new SolveOptions();
var solved = project.Solve(data, options);

// The user drags task "b" to January 5.
var drag = new SchedulingChanges();
drag.Tasks.Update.Add(new TaskUpdate("b") { StartDate = Day(5) });

var preview = project.Preview(drag, new PreviewOptions());
foreach (var update in preview.Updates)
    Console.WriteLine($"task {update.Id}: {update.StartDate} .. {update.EndDate}");

// The project still holds the solved dates: "b" starts on January 3.
Console.WriteLine(ReferenceEquals(solved, project.Solve(null, options))); // True

using Plen;

static Moment Day(int day) =>
    Moment.FromYmdHm(2026, 1, day, 0, 0) ?? throw new InvalidOperationException("invalid date");

var data = new ProjectData
{
    Tasks = [new TaskData("a") { StartDate = Day(1), Duration = 2.0 }],
};
data.Config.UseCalendars = false;

var project = new Project();
var options = new SolveOptions();
var loaded = project.Solve(data, options);

// The UI keeps the token of the dates it shows.
var shown = loaded.BaselineId;

var resize = new SchedulingChanges();
resize.Tasks.Update.Add(new TaskUpdate("a") { Duration = 3.0 });

var guarded = new PreviewOptions { BaselineId = shown };
var preview = project.Preview(resize, guarded);
// A preview reports the baseline it read, so its token works for the next preview too.
Console.WriteLine(preview.BaselineId == shown); // True

// Meanwhile, another edit is committed.
project.Apply(resize);

// Until the next solve there's no baseline to preview against.
try
{
    project.Preview(resize, new PreviewOptions());
}
catch (ProjectException e) when (e.Code == ProjectError.NoBaseline)
{
    Console.WriteLine("no baseline until the next solve");
}

var latest = project.Solve(null, options);

// The old token no longer names the baseline.
try
{
    project.Preview(resize, guarded);
}
catch (ProjectException e) when (e.Code == ProjectError.StaleBaseline)
{
    // Refresh the view from `latest`, then preview with its token.
    project.Preview(resize, new PreviewOptions { BaselineId = latest.BaselineId });
}

using Plen;

static Moment Day(int day) =>
    Moment.FromYmdHm(2026, 1, day, 0, 0) ?? throw new InvalidOperationException("invalid date");

var data = new ProjectData
{
    Tasks =
    [
        new TaskData("a") { StartDate = Day(1), Duration = 2.0 },
        new TaskData("b") { StartDate = Day(3), Duration = 1.0 },
    ],
    Resources = [new ResourceData { Id = "dev", Capacity = 1.0 }],
    Assignments =
    [
        new AssignmentData { Task = "a", Resource = "dev", Value = 1.0 },
        new AssignmentData { Task = "b", Resource = "dev", Value = 1.0 },
    ],
};
data.Config.UseCalendars = false;

var project = new Project();
project.Solve(data, new SolveOptions());

// Drag "b" one day earlier, onto the last day of "a".
var drag = new SchedulingChanges();
drag.Tasks.Update.Add(new TaskUpdate("b") { StartDate = Day(2) });

var options = new PreviewOptions
{
    Profile = new ProfileQuery(Day(1), Day(5)) { Tasks = ProfileTasks.Over },
};
var preview = project.Preview(drag, options);

if (preview.Profile is { } profile)
{
    foreach (var resource in profile.Resources)
    {
        foreach (var bucket in resource.Buckets.Where(b => b.Load > b.Capacity))
        {
            var tasks = string.Join(", ", bucket.Tasks ?? []);
            Console.WriteLine(
                $"{resource.Resource} overloaded at {bucket.Start}: {bucket.Load} of {bucket.Capacity} ({tasks})");
        }
    }
}

using Plen;

static Moment Day(int day) =>
    Moment.FromYmdHm(2026, 1, day, 0, 0) ?? throw new InvalidOperationException("invalid date");

static SchedulingChanges Resize(Id task, double duration)
{
    var changes = new SchedulingChanges();
    changes.Tasks.Update.Add(new TaskUpdate(task) { Duration = duration });
    return changes;
}

var data = new ProjectData
{
    Tasks =
    [
        new TaskData("a") { StartDate = Day(1), Duration = 2.0 },
        new TaskData("b") { StartDate = Day(1), Duration = 1.0 },
    ],
    Links = [new LinkData { Id = "ab", Source = "a", Target = "b" }],
};
data.Config.UseCalendars = false;

var options = new SolveOptions();
var project = new Project();
project.Solve(data, options);

// A cheap copy: it shares state with `project` until one of them is edited.
var draft = project.Clone();
draft.Apply(Resize("a", 4.0));
draft.Solve(null, options);
draft.Apply(Resize("b", 3.0));
var outcome = draft.Solve(null, options);

foreach (var update in outcome.Updates)
    Console.WriteLine($"draft task {update.Id}: {update.StartDate} .. {update.EndDate}");

// The original is untouched and still previews against its own baseline.
Console.WriteLine(project.Preview(new SchedulingChanges(), new PreviewOptions()).Updates.Count); // 0

// The user accepts the draft: keep it as the project.
project = draft;

using Plen;

static void ShowLevelingProposal(Project project)
{
    var draft = project.Clone();
    var leveled = draft.Level(new LevelingOptions());
    foreach (var update in leveled.Schedule.Updates)
        Console.WriteLine($"task {update.Id} delay {update.LevelingDelay}");
}