Pilz.Dalamud/Pilz.Dalamud/Tools/Strings/StringUpdateFactory.cs

using Dalamud.Game.Text.SeStringHandling;
using Dalamud.Game.Text.SeStringHandling.Payloads;

namespace Pilz.Dalamud.Tools.Strings;

public static class StringUpdateFactory
{
    public static void ApplyStringChanges(StringChangesProps props)
    {
        if (props.StringChanges != null && props.StringChanges.Any())
        {
            var seString = props.Destination;
            List<StringPosition> stringPositionsOrdered = GetOrderedStringPositions(props);

            foreach (var stringPosition in stringPositionsOrdered)
            {
                var stringChange = props.StringChanges.GetChange(stringPosition);
                if (stringChange != null && stringChange.Payloads.Any())
                {
                    AddSpacesBetweenTextPayloads(stringChange.Payloads, stringPosition);

                    if (stringPosition == StringPosition.Before)
                    {
                        Payload anchorFirst = stringChange.ForceUsingSingleAnchorPayload ? props.AnchorPayload : props.AnchorPayloads?.FirstOrDefault();

                        if (anchorFirst != null)
                        {
                            var anchorPayloadIndex = seString.Payloads.IndexOf(anchorFirst);
                            seString.Payloads.InsertRange(anchorPayloadIndex, stringChange.Payloads);
                        }
                        else
                            seString.Payloads.InsertRange(0, stringChange.Payloads);
                    }
                    else if (stringPosition == StringPosition.After)
                    {
                        Payload anchorLast = stringChange.ForceUsingSingleAnchorPayload ? props.AnchorPayload : props.AnchorPayloads?.LastOrDefault();

                        if (anchorLast != null)
                        {
                            var anchorPayloadIndex = seString.Payloads.IndexOf(anchorLast);
                            seString.Payloads.InsertRange(anchorPayloadIndex + 1, stringChange.Payloads);
                        }
                        else
                            seString.Payloads.AddRange(stringChange.Payloads);
                    }
                    else if (stringPosition == StringPosition.Replace)
                    {
                        Payload anchorReplace = props.AnchorPayload;

                        if (anchorReplace != null)
                        {
                            var anchorPayloadIndex = seString.Payloads.IndexOf(anchorReplace);
                            seString.Payloads.InsertRange(anchorPayloadIndex, stringChange.Payloads);
                            seString.Remove(anchorReplace);
                        }
                        else
                        {
                            seString.Payloads.Clear();
                            seString.Payloads.AddRange(stringChange.Payloads);
                        }
                    }
                }
            }
        }
    }

    private static void AddSpacesBetweenTextPayloads(List<Payload> payloads, StringPosition tagPosition)
    {
        if (payloads != null && payloads.Any())
        {
            var indicesToInsertSpacesAt = new List<int>();
            var lastTextPayloadIndex = -1;

            static TextPayload getNewTextPayload() => new(" ");

            foreach (var payload in payloads.Reverse<Payload>())
            {
                if (payload is IconPayload iconPayload)
                    lastTextPayloadIndex = -1;
                else if (payload is TextPayload textPayload)
                {
                    if (lastTextPayloadIndex != -1)
                        indicesToInsertSpacesAt.Add(payloads.IndexOf(textPayload) + 1);
                    lastTextPayloadIndex = payloads.IndexOf(textPayload);
                }
            }

            foreach (var indexToInsertSpaceAt in indicesToInsertSpacesAt)
                payloads.Insert(indexToInsertSpaceAt, getNewTextPayload());

            // Decide whether to add a space to the end
            if (tagPosition == StringPosition.Before)
            {
                var significantPayloads = payloads.Where(payload => payload is TextPayload || payload is IconPayload);
                if (significantPayloads.LastOrDefault() is TextPayload)
                    payloads.Add(getNewTextPayload());
            }
            // Decide whether to add a space to the beginning
            else if (tagPosition == StringPosition.After)
            {
                var significantPayloads = payloads.Where(payload => payload is TextPayload || payload is IconPayload);
                if (significantPayloads.FirstOrDefault() is TextPayload)
                    payloads.Insert(0, getNewTextPayload());
            }
        }
    }

    private static List<StringPosition> GetOrderedStringPositions(StringChangesProps props)
    {
        var tagPositionsOrdered = new List<StringPosition>();

        // If there's no anchor payload, do replaces first so that befores and afters are based on the replaced data
        if (props.AnchorPayloads == null || !props.AnchorPayloads.Any())
            tagPositionsOrdered.Add(StringPosition.Replace);

        tagPositionsOrdered.Add(StringPosition.Before);
        tagPositionsOrdered.Add(StringPosition.After);

        // If there is an anchor payload, do replaces last so that we still know which payload needs to be removed
        if (props.AnchorPayloads != null && props.AnchorPayloads.Any())
            tagPositionsOrdered.Add(StringPosition.Replace);

        return tagPositionsOrdered;
    }
}