using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using System.Text;

namespace FileInterface.Scheduler
{
    public sealed class CronJobExecutor
    {
        private readonly ICustomFunctionInvoker _invoker;
        private readonly JobLog _log;

        public CronJobExecutor(ICustomFunctionInvoker invoker, JobLog log)
        {
            _invoker = invoker;
            _log = log;
        }

        public void Execute(CronJobConfig job)
        {
            if (job.CallOnceWithoutFile)
            {
                ExecuteSingle(job, null);
                return;
            }

            if (!Directory.Exists(job.SourceDirectory))
            {
                _log.Error(job, "Source directory does not exist: " + job.SourceDirectory);
                return;
            }

            SearchOption option = job.IncludeSubdirectories ? SearchOption.AllDirectories : SearchOption.TopDirectoryOnly;
            string[] files;
            try
            {
                files = Directory.GetFiles(job.SourceDirectory, String.IsNullOrWhiteSpace(job.SearchPattern) ? "*.*" : job.SearchPattern, option)
                                 .OrderBy(f => f, StringComparer.OrdinalIgnoreCase)
                                 .ToArray();
            }
            catch (Exception ex)
            {
                _log.Error(job, "Cannot enumerate source files: " + ex.Message);
                return;
            }

            _log.Info(job, "Found " + files.Length + " file(s).");
            foreach (string file in files)
            {
                try { ExecuteSingle(job, file); }
                catch (Exception ex) { _log.Error(job, "File failed: " + file + " - " + ex.Message); }
            }
        }

        private void ExecuteSingle(CronJobConfig job, string file)
        {
            string rawContent = "";
            string processedContent = "";

            if (file != null)
            {
                // Opening with FileShare.ReadWrite prevents common producer/consumer lock issues.
                using (var stream = new FileStream(file, FileMode.Open, FileAccess.Read, FileShare.ReadWrite))
                using (var reader = new StreamReader(stream, Encoding.UTF8, true))
                    rawContent = reader.ReadToEnd();

                processedContent = ProcessContent(rawContent, job.RemoveEmptyLines, job.JoinSeparator);
            }

            string[] inArgs = (job.InArgs ?? new List<string>())
                .Select(arg => Expand(arg, job, file, rawContent, processedContent))
                .ToArray();

            _log.Info(job, "Calling CustomFunction '" + job.CustomFunction + "' with " + inArgs.Length + " inArg(s)" + (file == null ? "." : " for " + Path.GetFileName(file) + "."));
            CustomFunctionCallResult result = _invoker.Invoke(job.CustomFunction, inArgs);
            if (result == null) result = CustomFunctionCallResult.Fail("Invoker returned null.");

            if (!result.Success)
            {
                _log.Error(job, "CustomFunction failed: " + result.Message);
                return;
            }

            _log.Info(job, "CustomFunction succeeded: " + result.Message);
            if (file != null && job.MoveFileAfterSuccess)
            {
                string movedTo = MoveProcessedFile(file, job.MoveTargetDirectory, job.OverwriteTargetFile);
                _log.Info(job, "Moved file to: " + movedTo);
            }
        }

        private static string ProcessContent(string text, bool removeEmptyLines, string separator)
        {
            if (!removeEmptyLines) return text ?? "";
            string[] lines = (text ?? "").Replace("\r\n", "\n").Replace('\r', '\n').Split('\n');
            return String.Join(separator ?? ";", lines.Where(l => !String.IsNullOrWhiteSpace(l)).Select(l => l.Trim()));
        }

        private static string Expand(string template, CronJobConfig job, string file, string rawContent, string processedContent)
        {
            string value = template ?? "";
            string fullPath = file ?? "";
            string fileName = file == null ? "" : Path.GetFileName(file);
            string extension = file == null ? "" : Path.GetExtension(file);
            string directory = file == null ? "" : Path.GetDirectoryName(file);

            return value
                .Replace("{{CONTENT}}", processedContent ?? "")
                .Replace("{{RAW_CONTENT}}", rawContent ?? "")
                .Replace("{{FILE_NAME}}", fileName ?? "")
                .Replace("{{FILE_PATH}}", fullPath)
                .Replace("{{FILE_DIR}}", directory ?? "")
                .Replace("{{FILE_EXT}}", extension ?? "")
                .Replace("{{JOB_NAME}}", job.Name ?? "")
                .Replace("{{NOW}}", DateTime.Now.ToString("yyyy-MM-ddTHH:mm:ss.fffK"));
        }

        private static string MoveProcessedFile(string source, string targetDirectory, bool overwrite)
        {
            Directory.CreateDirectory(targetDirectory);
            string target = Path.Combine(targetDirectory, Path.GetFileName(source));

            if (File.Exists(target))
            {
                if (overwrite) File.Delete(target);
                else
                {
                    string name = Path.GetFileNameWithoutExtension(source);
                    string ext = Path.GetExtension(source);
                    target = Path.Combine(targetDirectory, name + "_" + DateTime.Now.ToString("yyyyMMdd_HHmmss_fff") + ext);
                    int i = 1;
                    while (File.Exists(target))
                    {
                        target = Path.Combine(targetDirectory, name + "_" + DateTime.Now.ToString("yyyyMMdd_HHmmss_fff") + "_" + i + ext);
                        i++;
                    }
                }
            }

            File.Move(source, target);
            return target;
        }
    }
}