using System.Text.RegularExpressions;
using Common.Extensions;
using Flurl;
using Flurl.Http;
using Serilog;
using TrashLib.Sonarr.Config;

namespace TrashLib.Sonarr.ReleaseProfile;

internal class ReleaseProfileGuideParser : IReleaseProfileGuideParser
{
    private readonly Dictionary<ReleaseProfileType, string> _markdownDocNames = new()
    {
        {ReleaseProfileType.Anime, "Sonarr-Release-Profile-RegEx-Anime"},
        {ReleaseProfileType.Series, "Sonarr-Release-Profile-RegEx"}
    };

    private readonly (TermCategory, Regex)[] _regexCategories =
    {
        (TermCategory.Required, BuildRegex(@"must contain")),
        (TermCategory.Ignored, BuildRegex(@"must not contain")),
        (TermCategory.Preferred, BuildRegex(@"preferred"))
    };

    private readonly Regex _regexHeader = new(@"^(#+)\s(.+?)\s*$", RegexOptions.Compiled);
    private readonly Regex _regexHeaderReleaseProfile = BuildRegex(@"release profile");
    private readonly Regex _regexPotentialScore = BuildRegex(@"\[(-?[\d]+)\]");
    private readonly Regex _regexScore = BuildRegex(@"score.*?\[(-?[\d]+)\]");

    public ReleaseProfileGuideParser(ILogger logger)
    {
        Log = logger;
    }

    private ILogger Log { get; }

    public async Task<string> GetMarkdownData(ReleaseProfileType profileName)
    {
        return await BuildUrl(profileName).GetStringAsync();
    }

    public IDictionary<string, ProfileData> ParseMarkdown(ReleaseProfileConfig config, string markdown)
    {
        var state = new ParserState(Log);

        var reader = new StringReader(markdown);
        for (var line = reader.ReadLine(); line != null; line = reader.ReadLine())
        {
            state.LineNumber++;
            if (string.IsNullOrEmpty(line))
            {
                continue;
            }

            // Always check if we're starting a fenced code block. Whether we are inside one or not greatly affects
            // the logic we use.
            if (line.StartsWith("```"))
            {
                state.InsideCodeBlock = !state.InsideCodeBlock;
                continue;
            }

            // Not inside brackets
            if (!state.InsideCodeBlock)
            {
                OutsideFence_ParseMarkdown(line, state);
            }
            // Inside brackets
            else
            {
                if (!state.IsValid)
                {
                    Log.Debug("  - !! Inside bracket with invalid state; skipping! " +
                              "[Profile Name: {ProfileName}] " +
                              "[Category: {Category}] " + "[Score: {Score}] " + "[Line: {Line}] ",
                        state.ProfileName,
                        state.CurrentCategory.Value, state.Score, line);
                }
                else
                {
                    InsideFence_ParseMarkdown(config, line, state);
                }
            }
        }

        Log.Debug("\n");
        return state.Results;
    }

    private bool IsSkippableLine(string line)
    {
        // Skip lines with leading whitespace (i.e. indentation).
        // These lines will almost always be `!!! attention` blocks of some kind and won't contain useful data.
        if (char.IsWhiteSpace(line, 0))
        {
            Log.Debug("  - Skip Indented Line: {Line}", line);
            return true;
        }

        // Lines that begin with `???` or `!!!` are admonition syntax (extended markdown supported by Python)
        if (line.StartsWith("!!!") || line.StartsWith("???"))
        {
            Log.Debug("  - Skip Admonition: {Line}", line);
            return true;
        }

        return false;
    }

    private static Regex BuildRegex(string regex)
    {
        return new Regex(regex, RegexOptions.Compiled | RegexOptions.IgnoreCase);
    }

    private Url BuildUrl(ReleaseProfileType profileName)
    {
        return "https://raw.githubusercontent.com/TRaSH-/Guides/master/docs/Sonarr".AppendPathSegment(
            $"{_markdownDocNames[profileName]}.md");
    }

    private void InsideFence_ParseMarkdown(ReleaseProfileConfig config, string line, ParserState state)
    {
        // Sometimes a comma is present at the end of these lines, because when it's
        // pasted into Sonarr it acts as a delimiter. However, when using them with the
        // API we do not need them.
        line = line.TrimEnd(',');

        var category = state.CurrentCategory.Value;
        switch (category!.Value)
        {
            case TermCategory.Preferred:
            {
                Log.Debug("    + Capture Term " +
                          "[Category: {CurrentCategory}] " +
                          "[Optional: {Optional}] " +
                          "[Score: {Score}] " +
                          "[Strict: {StrictNegativeScores}] " +
                          "[Term: {Line}]",
                    category.Value, state.TermsAreOptional.Value, state.Score, config.StrictNegativeScores, line);

                if (config.StrictNegativeScores && state.Score < 0)
                {
                    state.IgnoredTerms.Add(line);
                }
                else
                {
                    // Score is already checked for null prior to the method being invoked.
                    var prefList = state.PreferredTerms.GetOrCreate(state.Score!.Value);
                    prefList.Add(line);
                }

                break;
            }

            case TermCategory.Ignored:
            {
                state.IgnoredTerms.Add(line);
                Log.Debug("    + Capture Term " +
                          "[Category: {Category}] " +
                          "[Optional: {Optional}] " +
                          "[Term: {Line}]",
                    category.Value, state.TermsAreOptional.Value, line);
                break;
            }

            case TermCategory.Required:
            {
                state.RequiredTerms.Add(line);
                Log.Debug("    + Capture Term " +
                          "[Category: {Category}] " +
                          "[Optional: {Optional}] " +
                          "[Term: {Line}]",
                    category.Value, state.TermsAreOptional.Value, line);
                break;
            }

            default:
            {
                throw new ArgumentOutOfRangeException($"Unknown term category: {category.Value}");
            }
        }
    }

    private void OutsideFence_ParseMarkdown(string line, ParserState state)
    {
        // ReSharper disable once InlineOutVariableDeclaration
        Match match;

        // Header Processing. Never do any additional processing to headers, so return after processing it
        if (_regexHeader.Match(line, out match))
        {
            OutsideFence_ParseHeader(state, match);
            return;
        }

        // Until we find a header that defines a profile, we don't care about anything under it.
        if (string.IsNullOrEmpty(state.ProfileName))
        {
            return;
        }

        // These are often found in admonition (indented) blocks, so we check for it before we
        // run the IsSkippableLine() check.
        if (line.ContainsIgnoreCase("include preferred"))
        {
            state.GetProfile().IncludePreferredWhenRenaming = !line.ContainsIgnoreCase("not");
            Log.Debug("  - 'Include Preferred' found [Value: {IncludePreferredWhenRenaming}] [Line: {Line}]",
                state.GetProfile().IncludePreferredWhenRenaming, line);
            return;
        }

        if (IsSkippableLine(line))
        {
            return;
        }

        OutsideFence_ParseInformationOnSameLine(line, state);
    }

    private void OutsideFence_ParseHeader(ParserState state, Match match)
    {
        var headerDepth = match.Groups[1].Length;
        var headerText = match.Groups[2].Value;
        state.CurrentHeaderDepth = headerDepth;

        // Always reset the scope-based state any time we see a header, regardless of depth or phrasing.
        // Each header "resets" scope-based state, even if it's entering into a nested header, which usually will
        // not reset as much state.
        state.ResetScopeState(headerDepth);

        Log.Debug("> Parsing Header [Nested: {Nested}] [Depth: {HeaderDepth}] [Text: {HeaderText}]",
            headerDepth > state.ProfileHeaderDepth, headerDepth, headerText);

        // Profile name (always reset previous state here)
        if (_regexHeaderReleaseProfile.Match(headerText).Success)
        {
            state.ResetParserState();
            state.ProfileName = headerText;
            state.ProfileHeaderDepth = headerDepth;
            Log.Debug("  - New Profile [Text: {HeaderText}]", headerText);
        }
        else if (headerDepth <= state.ProfileHeaderDepth)
        {
            Log.Debug("  - !! Non-nested, non-profile header found; resetting all state");
            state.ResetParserState();
        }

        // If a single header can be parsed with multiple phrases, add more if conditions below this comment.
        // In order to make sure all checks happen as needed, do not return from the condition (to allow conditions
        // below it to be executed)

        // Another note: Any "state" set by headers has longer lasting effects. That state will remain in effect
        // until the next header. That means multiple fenced code blocks will be impacted.

        ParseAndSetOptional(headerText, state);
        ParseAndSetCategory(headerText, state);
    }

    private void OutsideFence_ParseInformationOnSameLine(string line, ParserState state)
    {
        // ReSharper disable once InlineOutVariableDeclaration
        Match match;

        ParseAndSetOptional(line, state);
        ParseAndSetCategory(line, state);

        if (_regexScore.Match(line, out match))
        {
            // As a convenience, if we find a score, we obviously should set the category to Preferred even if
            // the guide didn't explicitly mention that.
            state.CurrentCategory.PushValue(TermCategory.Preferred, state.CurrentHeaderDepth);

            state.Score = int.Parse(match.Groups[1].Value);
            Log.Debug("  - Score [Value: {Score}]", state.Score);
        }
        else if (_regexPotentialScore.Match(line, out match))
        {
            Log.Warning("Found a potential score on line #{Line} that will be ignored because the " +
                        "word 'score' is missing (This is probably a bug in the guide itself): {ScoreMatch}",
                state.LineNumber, match.Groups[0].Value);
        }
    }

    private void ParseAndSetCategory(string line, ParserState state)
    {
        var category = ParseCategory(line);
        if (category == null)
        {
            return;
        }

        state.CurrentCategory.PushValue(category.Value, state.CurrentHeaderDepth);

        Log.Debug("  - Category Set " +
                  "[Scope: {Scope}] " +
                  "[Name: {Category}] " +
                  "[Stack Size: {StackSize}] " +
                  "[Line: {Line}]",
            category.Value, state.CurrentHeaderDepth, state.CurrentCategory.StackSize, line);
    }

    private void ParseAndSetOptional(string line, ParserState state)
    {
        if (line.ContainsIgnoreCase("optional"))
        {
            state.TermsAreOptional.PushValue(true, state.CurrentHeaderDepth);

            Log.Debug("  - Optional Set " +
                      "[Scope: {Scope}] " +
                      "[Stack Size: {StackSize}] " +
                      "[Line: {Line}]",
                state.CurrentHeaderDepth, state.CurrentCategory.StackSize, line);
        }
    }

    private TermCategory? ParseCategory(string line)
    {
        foreach (var (category, regex) in _regexCategories)
        {
            if (regex.Match(line).Success)
            {
                return category;
            }
        }

        return null;
    }
}