using System;
using System.Diagnostics;
using System.IO;

namespace Implab.Diagnostics {
    public class SimpleTraceListener : TextWriterTraceListener {
        public SimpleTraceListener() {
        }

        public SimpleTraceListener(Stream stream) : base(stream) {
        }

        public SimpleTraceListener(TextWriter writer) : base(writer) {
        }

        public SimpleTraceListener(string fileName) : base(fileName) {
        }

        public SimpleTraceListener(Stream stream, string name) : base(stream, name) {
        }

        public SimpleTraceListener(TextWriter writer, string name) : base(writer, name) {
        }

        public SimpleTraceListener(string fileName, string name) : base(fileName, name) {
        }

        public override void TraceData(TraceEventCache eventCache, string source, TraceEventType eventType, int id, object data) {
            switch (id) {
                case TraceEventCodes.StartLogicalOperation:
                    TraceEvent(eventCache, source, eventType, id, "+{0}", data);
                    break;
                case TraceEventCodes.StopLogicalOperation:
                    TraceEvent(eventCache, source, eventType, id, FormatStopLogicalOperation(data));
                    break;
                default:
                    TraceEvent(eventCache, source, eventType, id, data?.ToString());
                    break;
            }
        }

        string FormatStopLogicalOperation(object data) {
            if (data is LogicalOperation op) {
                return string.Format("-{0} ({1})", op, FormatTimespan(op.Elapsed));
            } else {
                return data?.ToString();
            }
        }

        string FormatTimespan(TimeSpan value) {
            if (value.TotalSeconds < 10) {
                return value.Milliseconds.ToString() + "ms";
            } else if (value.TotalSeconds < 30) {
                return string.Format("{0:0.###}s", value.TotalSeconds);
            } else {
                return value.ToString();
            }
        }

        public override void TraceData(TraceEventCache eventCache, string source, TraceEventType eventType, int id, params object[] data) {
            var prev = IndentLevel;
            IndentLevel += eventCache.LogicalOperationStack.Count;
            try {
                base.TraceData(eventCache, source, eventType, id, data);
            } finally {
                IndentLevel = prev;
            }
        }

        public override void TraceEvent(TraceEventCache eventCache, string source, TraceEventType eventType, int id) {
            var prev = IndentLevel;
            IndentLevel += eventCache.LogicalOperationStack.Count;
            try {
                base.TraceEvent(eventCache, source, eventType, id);
            } finally {
                IndentLevel = prev;
            }
        }

        public override void TraceEvent(TraceEventCache eventCache, string source, TraceEventType eventType, int id, string format, params object[] args) {
            TraceEvent(eventCache, source, eventType, id, String.Format(format, args));
        }

        public override void TraceEvent(TraceEventCache eventCache, string source, TraceEventType eventType, int id, string message) {
            var prev = IndentLevel;
            IndentLevel += eventCache.LogicalOperationStack.Count;
            try {
                LogicalOperation operation = null;
                if (eventCache.LogicalOperationStack.Count > 0)
                    operation = eventCache.LogicalOperationStack.Peek() as LogicalOperation;

                if (operation != null) {
                    base.TraceData(eventCache, source, eventType, id, FormatTimespan(operation.Elapsed) + ": " + message);
                } else {
                    base.TraceData(eventCache, source, eventType, id, message);
                }
            } finally {
                IndentLevel = prev;
            }
        }

        public override void TraceTransfer(TraceEventCache eventCache, string source, int id, string message, Guid relatedActivityId) {
            var prev = IndentLevel;
            IndentLevel += eventCache.LogicalOperationStack.Count;
            try {
                base.TraceTransfer(eventCache, source, id, message, relatedActivityId);
            } finally {
                IndentLevel = prev;
            }
        }


    }
}