/*
 * Copyright (c) 2020-2021, the SerenityOS developers.
 *
 * SPDX-License-Identifier: BSD-2-Clause
 */

#pragma once

#include <AK/Noncopyable.h>
#include <AK/WeakPtr.h>
#include <LibGUI/TextDocument.h>
#include <LibGfx/Palette.h>
#include <LibSyntax/HighlighterClient.h>

namespace Syntax {

enum class Language {
    Cpp,
    CSS,
    GML,
    HTML,
    INI,
    JavaScript,
    PlainText,
    SQL,
    Shell,
};

struct TextStyle {
    const Gfx::Color color;
    const bool bold { false };
};

class Highlighter {
    AK_MAKE_NONCOPYABLE(Highlighter);
    AK_MAKE_NONMOVABLE(Highlighter);

public:
    virtual ~Highlighter();

    virtual Language language() const = 0;
    virtual void rehighlight(const Palette&) = 0;
    virtual void highlight_matching_token_pair();

    virtual bool is_identifier(u64) const { return false; };
    virtual bool is_navigatable(u64) const { return false; };

    void attach(HighlighterClient&);
    void detach();
    void cursor_did_change();

    struct MatchingTokenPair {
        u64 open;
        u64 close;
    };
    Vector<MatchingTokenPair> matching_token_pairs() const;

protected:
    Highlighter() { }

    // FIXME: This should be WeakPtr somehow
    HighlighterClient* m_client { nullptr };

    virtual Vector<MatchingTokenPair> matching_token_pairs_impl() const = 0;
    virtual bool token_types_equal(u64, u64) const = 0;
    void register_nested_token_pairs(Vector<MatchingTokenPair>);
    void clear_nested_token_pairs() { m_nested_token_pairs.clear(); }
    size_t first_free_token_kind_serial_value() const { return m_nested_token_pairs.size(); }

    struct BuddySpan {
        int index { -1 };
        GUI::TextDocumentSpan span_backup;
    };

    bool m_has_brace_buddies { false };
    BuddySpan m_brace_buddies[2];
    HashTable<MatchingTokenPair> m_nested_token_pairs;
};

class ProxyHighlighterClient final : public Syntax::HighlighterClient {
public:
    ProxyHighlighterClient(Syntax::HighlighterClient& client, GUI::TextPosition start, u64 nested_kind_start_value, StringView source)
        : m_document(client.get_document())
        , m_text(source)
        , m_start(start)
        , m_nested_kind_start_value(nested_kind_start_value)
    {
    }

    Vector<GUI::TextDocumentSpan> corrected_spans() const
    {
        Vector<GUI::TextDocumentSpan> spans { m_spans };
        for (auto& entry : spans) {
            entry.range.start() = {
                entry.range.start().line() + m_start.line(),
                entry.range.start().line() == 0 ? entry.range.start().column() + m_start.column() : entry.range.start().column(),
            };
            entry.range.end() = {
                entry.range.end().line() + m_start.line(),
                entry.range.end().line() == 0 ? entry.range.end().column() + m_start.column() : entry.range.end().column(),
            };
            if (entry.data != (u64)-1)
                entry.data += m_nested_kind_start_value;
        }

        return spans;
    }

    Vector<Syntax::Highlighter::MatchingTokenPair> corrected_token_pairs(Vector<Syntax::Highlighter::MatchingTokenPair> pairs) const
    {
        for (auto& pair : pairs) {
            pair.close += m_nested_kind_start_value;
            pair.open += m_nested_kind_start_value;
        }
        return pairs;
    }

private:
    virtual Vector<GUI::TextDocumentSpan>& spans() override { return m_spans; }
    virtual const Vector<GUI::TextDocumentSpan>& spans() const override { return m_spans; }
    virtual void set_span_at_index(size_t index, GUI::TextDocumentSpan span) override { m_spans.at(index) = move(span); }

    virtual String highlighter_did_request_text() const override { return m_text; }
    virtual void highlighter_did_request_update() override { }
    virtual GUI::TextDocument& highlighter_did_request_document() override { return m_document; }
    virtual GUI::TextPosition highlighter_did_request_cursor() const override { return {}; }
    virtual void highlighter_did_set_spans(Vector<GUI::TextDocumentSpan> spans) override { m_spans = move(spans); }

    Vector<GUI::TextDocumentSpan> m_spans;
    GUI::TextDocument& m_document;
    StringView m_text;
    GUI::TextPosition m_start;
    u64 m_nested_kind_start_value { 0 };
};

}

template<>
struct AK::Traits<Syntax::Highlighter::MatchingTokenPair> : public AK::GenericTraits<Syntax::Highlighter::MatchingTokenPair> {
    static unsigned hash(Syntax::Highlighter::MatchingTokenPair const& pair)
    {
        return pair_int_hash(u64_hash(pair.open), u64_hash(pair.close));
    }
    static bool equals(Syntax::Highlighter::MatchingTokenPair const& a, Syntax::Highlighter::MatchingTokenPair const& b)
    {
        return a.open == b.open && a.close == b.close;
    }
};