using System.Text.Json;

namespace URLNotesGrabberCORE
{
    // Port of ThreeTxtFileHelper/UpdateBlogPaths.cs. Reads .tumblr / .tmblrpriv metadata
    // files from a root\Index folder and populates Blogs.TTFolderPath in TL.db.
    //
    // Scan() is the reusable engine: --updatepaths wraps it as a standalone command and
    // --output calls it as a refresh step, because a TL.db synced between machines cannot
    // hold one absolute path that is correct on both.
    public static class UpdateBlogPathsRunner
    {
        public enum ScanOutcome
        {
            Completed,
            NoRootConfigured,
            IndexFolderMissing
        }

        public sealed class ScanResult
        {
            public ScanOutcome Outcome { get; init; }
            public string RootPath { get; init; } = string.Empty;
            public string IndexPath { get; init; } = string.Empty;
            public int MetadataFiles { get; init; }
            public int Written { get; init; }
            public int Unchanged { get; init; }
            public int NoLocation { get; init; }
            public int NoMatchingRow { get; init; }
            public int Errors { get; init; }
        }

        // verbose: log a line per metadata file. --updatepaths wants that detail; --output
        // only wants the counts, since a few hundred lines before the export would bury it.
        public static ScanResult Scan(string? rootPath, bool verbose)
        {
            if (string.IsNullOrWhiteSpace(rootPath))
                return new ScanResult { Outcome = ScanOutcome.NoRootConfigured };

            DataAccess.EnsureTTFileHelperColumnsExist();

            string indexPath = Path.Combine(rootPath, "Index");
            if (!Directory.Exists(indexPath))
            {
                return new ScanResult
                {
                    Outcome = ScanOutcome.IndexFolderMissing,
                    RootPath = rootPath,
                    IndexPath = indexPath
                };
            }

            var blogFiles = Directory.GetFiles(indexPath, "*.tumblr")
                .Concat(Directory.GetFiles(indexPath, "*.tmblrpriv"))
                .ToList();

            if (verbose)
                Console.WriteLine($"Found {blogFiles.Count} blog metadata files");

            int updatedCount = 0;
            int unchangedCount = 0;
            int noLocationCount = 0;
            int noRowCount = 0;
            int errorCount = 0;

            foreach (var blogFile in blogFiles)
            {
                try
                {
                    string blogName = Path.GetFileNameWithoutExtension(blogFile);
                    string jsonContent = File.ReadAllText(blogFile);
                    using JsonDocument doc = JsonDocument.Parse(jsonContent);
                    JsonElement root = doc.RootElement;

                    if (root.TryGetProperty("FileDownloadLocation", out JsonElement locationElement))
                    {
                        string? fileDownloadLocation = locationElement.GetString()?.Trim();
                        if (!string.IsNullOrWhiteSpace(fileDownloadLocation))
                        {
                            // Report the database's answer, not the fact that the file parsed.
                            if (DataAccess.SetBlogTTFolderPath(blogName, fileDownloadLocation))
                            {
                                updatedCount++;
                                if (verbose)
                                    Console.WriteLine($"Updated {blogName}: {fileDownloadLocation}");
                            }
                            else if (DataAccess.BlogExists(blogName))
                            {
                                unchangedCount++;
                            }
                            else
                            {
                                noRowCount++;
                                Console.WriteLine($"No Blogs row named '{blogName}' -- path not stored (name may differ in case)");
                            }
                        }
                        else
                        {
                            noLocationCount++;
                            if (verbose)
                                Console.WriteLine($"Empty FileDownloadLocation in {blogFile}");
                        }
                    }
                    else
                    {
                        noLocationCount++;
                        if (verbose)
                            Console.WriteLine($"No FileDownloadLocation found in {blogFile}");
                    }
                }
                catch (Exception ex)
                {
                    errorCount++;
                    Console.WriteLine($"Error processing {blogFile}: {ex.Message}");
                }
            }

            return new ScanResult
            {
                Outcome = ScanOutcome.Completed,
                RootPath = rootPath,
                IndexPath = indexPath,
                MetadataFiles = blogFiles.Count,
                Written = updatedCount,
                Unchanged = unchangedCount,
                NoLocation = noLocationCount,
                NoMatchingRow = noRowCount,
                Errors = errorCount
            };
        }

        public static int Run(string rootPath)
        {
            if (string.IsNullOrWhiteSpace(rootPath))
            {
                Console.WriteLine("UpdateBlogPaths: rootPath is required.");
                return 1;
            }

            string indexPath = Path.Combine(rootPath, "Index");
            Console.WriteLine($"Scanning Index folder: {indexPath}");

            var result = Scan(rootPath, verbose: true);

            if (result.Outcome == ScanOutcome.IndexFolderMissing)
            {
                Console.WriteLine($"Index folder not found at: {result.IndexPath}");
                return 1;
            }

            Console.WriteLine($"\n========== UpdateBlogPaths summary ==========");
            Console.WriteLine($"Metadata files:           {result.MetadataFiles}");
            Console.WriteLine($"TTFolderPath written:     {result.Written}");
            Console.WriteLine($"Already correct:          {result.Unchanged}");
            Console.WriteLine($"No FileDownloadLocation:  {result.NoLocation}");
            Console.WriteLine($"No matching blog row:     {result.NoMatchingRow}");
            Console.WriteLine($"Errors:                   {result.Errors}");

            Console.WriteLine($"\nBlogs now holding a TTFolderPath: {DataAccess.CountBlogsWithTTFolderPath()}");

            return result.Errors == 0 ? 0 : 2;
        }
    }
}