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

namespace FastSeekWpf.Core;

public enum ResultKind
{
    App, Document, Image, Video, Audio, Archive, Folder, Other
}

public class SearchResult
{
    public string FullPath { get; set; } = string.Empty;
    public string Name { get; set; } = string.Empty;
    public byte Rank { get; set; }
    public bool IsDir { get; set; }
    public ResultKind Kind { get; set; }
}

public static class SearchEngine
{
    private static readonly string[] AppExtensions = { "exe", "lnk", "msi", "appx", "msix" };
    private static readonly string[] AppPathMarkers = {
        "\\program files\\", "\\program files (x86)\\",
        "\\start menu\\", "\\desktop\\", "\\appdata\\"
    };

    private static readonly Dictionary<string, ResultKind> ExtensionMap = new(StringComparer.OrdinalIgnoreCase)
    {
        ["exe"] = ResultKind.App, ["lnk"] = ResultKind.App, ["msi"] = ResultKind.App,
        ["doc"] = ResultKind.Document, ["docx"] = ResultKind.Document, ["pdf"] = ResultKind.Document,
        ["txt"] = ResultKind.Document, ["xlsx"] = ResultKind.Document, ["xls"] = ResultKind.Document,
        ["pptx"] = ResultKind.Document, ["ppt"] = ResultKind.Document, ["odt"] = ResultKind.Document,
        ["ods"] = ResultKind.Document, ["odp"] = ResultKind.Document, ["rtf"] = ResultKind.Document,
        ["md"] = ResultKind.Document, ["csv"] = ResultKind.Document, ["json"] = ResultKind.Document,
        ["xml"] = ResultKind.Document, ["yaml"] = ResultKind.Document, ["toml"] = ResultKind.Document,
        ["ini"] = ResultKind.Document, ["log"] = ResultKind.Document,
        ["png"] = ResultKind.Image, ["jpg"] = ResultKind.Image, ["jpeg"] = ResultKind.Image,
        ["gif"] = ResultKind.Image, ["bmp"] = ResultKind.Image, ["webp"] = ResultKind.Image,
        ["svg"] = ResultKind.Image, ["ico"] = ResultKind.Image, ["tiff"] = ResultKind.Image,
        ["heic"] = ResultKind.Image, ["raw"] = ResultKind.Image, ["psd"] = ResultKind.Image,
        ["mp4"] = ResultKind.Video, ["mkv"] = ResultKind.Video, ["avi"] = ResultKind.Video,
        ["mov"] = ResultKind.Video, ["wmv"] = ResultKind.Video, ["flv"] = ResultKind.Video,
        ["webm"] = ResultKind.Video, ["m4v"] = ResultKind.Video,
        ["mp3"] = ResultKind.Audio, ["flac"] = ResultKind.Audio, ["wav"] = ResultKind.Audio,
        ["aac"] = ResultKind.Audio, ["ogg"] = ResultKind.Audio, ["m4a"] = ResultKind.Audio,
        ["wma"] = ResultKind.Audio, ["opus"] = ResultKind.Audio,
        ["zip"] = ResultKind.Archive, ["rar"] = ResultKind.Archive, ["7z"] = ResultKind.Archive,
        ["tar"] = ResultKind.Archive, ["gz"] = ResultKind.Archive, ["bz2"] = ResultKind.Archive,
        ["xz"] = ResultKind.Archive, ["zst"] = ResultKind.Archive,
    };

    public static ResultKind GetKind(string? ext, bool isDir, string fullPathLower)
    {
        if (isDir) return ResultKind.Folder;
        if (ext == null) return ResultKind.Other;
        if (ExtensionMap.TryGetValue(ext, out var kind))
        {
            if (kind == ResultKind.App && ContainsAny(fullPathLower, AppPathMarkers))
                return ResultKind.App;
            return kind;
        }
        return ResultKind.Other;
    }

    private static bool ContainsAny(string s, string[] markers)
    {
        foreach (var m in markers)
            if (s.Contains(m, StringComparison.Ordinal)) return true;
        return false;
    }

    // Search — matches Rust search() exactly. Uses IndexStore.Name() / NameLower() / BuildPath()
    public static List<SearchResult> Search(
        IndexStore store,
        string query,
        int limit,
        bool caseSensitive,
        List<string> excludedDirs)
    {
        if (string.IsNullOrEmpty(query))
            return new List<SearchResult>();

        string q = caseSensitive ? query : query.ToLowerInvariant();

        // Phase 1: lightweight name-only matching
        var candidates = new List<(int idx, byte rank)>();

        for (int i = 0; i < store.Entries.Count; i++)
        {
            var entry = store.Entries[i];
            string nameCmp = caseSensitive ? store.Name(entry) : store.NameLower(entry);

            byte rank;
            if (nameCmp == q) rank = 1;
            else if (nameCmp.StartsWith(q, StringComparison.Ordinal)) rank = 2;
            else if (nameCmp.Contains(q, StringComparison.Ordinal)) rank = 3;
            else continue;

            candidates.Add((i, rank));
        }

        // Phase 2: sort by rank, keep overshoot buffer
        candidates.Sort((a, b) => a.rank.CompareTo(b.rank));
        int overshoot = Math.Max(limit * 5, 1000);
        if (candidates.Count > overshoot)
            candidates.RemoveRange(overshoot, candidates.Count - overshoot);

        // Phase 3: build paths + exclusions + app promotion
        var results = new List<SearchResult>(limit);

        foreach (var (idx, baseRank) in candidates)
        {
            var entry = store.Entries[idx];
            string fullPath = store.BuildPath(entry.FileRef);

            if (excludedDirs.Count > 0)
            {
                string pathLower = fullPath.ToLowerInvariant();
                if (excludedDirs.Any(ex => pathLower.StartsWith(ex, StringComparison.Ordinal)))
                    continue;
            }

            string nameLower = store.NameLower(entry);
            byte rank = baseRank;
            if (baseRank <= 2)
            {
                string? ext = nameLower.Contains('.') ? nameLower[(nameLower.LastIndexOf('.') + 1)..] : null;
                if (ext != null && Array.IndexOf(AppExtensions, ext) >= 0)
                {
                    string pathLower = fullPath.ToLowerInvariant();
                    if (ContainsAny(pathLower, AppPathMarkers))
                        rank = 0;
                }
            }

            string? fileExt = null;
            if (!entry.IsDir)
            {
                string name = store.Name(entry);
                int dot = name.LastIndexOf('.');
                if (dot >= 0) fileExt = name[(dot + 1)..].ToLowerInvariant();
            }

            results.Add(new SearchResult
            {
                FullPath = fullPath,
                Name = store.Name(entry),
                Rank = rank,
                IsDir = entry.IsDir,
                Kind = GetKind(fileExt, entry.IsDir, fullPath.ToLowerInvariant())
            });
        }

        results.Sort((a, b) => a.Rank.CompareTo(b.Rank));
        if (results.Count > limit)
            results.RemoveRange(limit, results.Count - limit);

        return results;
    }

    // Extension search — matches Rust extension filtering in main.rs
    public static List<SearchResult> SearchByExtension(
        IndexStore store,
        string ext,
        List<string> excludedDirs)
    {
        string dotExt = "." + ext.ToLowerInvariant();
        var results = new List<SearchResult>();

        for (int i = 0; i < store.Entries.Count; i++)
        {
            var entry = store.Entries[i];
            string name = store.NameLower(entry);
            if (!name.EndsWith(dotExt)) continue;

            string fullPath = store.BuildPath(entry.FileRef);
            string fullPathLower = fullPath.ToLowerInvariant();

            bool excluded = false;
            foreach (var ex in excludedDirs)
            {
                if (fullPathLower.StartsWith(ex, StringComparison.Ordinal))
                { excluded = true; break; }
            }
            if (excluded) continue;

            string? fileExt = null;
            int dot = name.LastIndexOf('.');
            if (dot >= 0) fileExt = name[(dot + 1)..];

            results.Add(new SearchResult
            {
                FullPath = fullPath,
                Name = store.Name(entry),
                Rank = 0,
                IsDir = entry.IsDir,
                Kind = GetKind(fileExt, entry.IsDir, fullPathLower)
            });

            if (results.Count >= 50) break;
        }

        return results;
    }
}