#pragma once

#include <vcpkg/base/cstringview.h>
#include <vcpkg/base/optional.h>
#include <vcpkg/base/stringview.h>
#include <vcpkg/base/unicode.h>

#include <vcpkg/textrowcol.h>

#include <memory>
#include <string>

namespace vcpkg::Parse
{
    struct IParseError
    {
        virtual ~IParseError() = default;
        virtual std::string format() const = 0;
    };

    struct ParseError : IParseError
    {
        ParseError(std::string origin, int row, int column, int caret_col, std::string line, std::string message)
            : origin(std::move(origin))
            , row(row)
            , column(column)
            , caret_col(caret_col)
            , line(std::move(line))
            , message(std::move(message))
        {
        }

        const std::string origin;
        const int row;
        const int column;
        const int caret_col;
        const std::string line;
        const std::string message;

        virtual std::string format() const override;
    };

    struct ParserBase
    {
        struct SourceLoc
        {
            Unicode::Utf8Decoder it;
            Unicode::Utf8Decoder start_of_line;
            int row;
            int column;
        };

        ParserBase(StringView text, StringView origin, TextRowCol init_rowcol = {});

        static constexpr bool is_whitespace(char32_t ch) { return ch == ' ' || ch == '\t' || ch == '\r' || ch == '\n'; }
        static constexpr bool is_lower_alpha(char32_t ch) { return ch >= 'a' && ch <= 'z'; }
        static constexpr bool is_upper_alpha(char32_t ch) { return ch >= 'A' && ch <= 'Z'; }
        static constexpr bool is_ascii_digit(char32_t ch) { return ch >= '0' && ch <= '9'; }
        static constexpr bool is_lineend(char32_t ch) { return ch == '\r' || ch == '\n' || ch == Unicode::end_of_file; }
        static constexpr bool is_alphanum(char32_t ch)
        {
            return is_upper_alpha(ch) || is_lower_alpha(ch) || is_ascii_digit(ch);
        }
        static constexpr bool is_alphanumdash(char32_t ch) { return is_alphanum(ch) || ch == '-'; }

        StringView skip_whitespace() { return match_zero_or_more(is_whitespace); }
        StringView skip_tabs_spaces()
        {
            return match_zero_or_more([](char32_t ch) { return ch == ' ' || ch == '\t'; });
        }
        void skip_to_eof() { m_it = m_it.end(); }
        void skip_newline()
        {
            if (cur() == '\r') next();
            if (cur() == '\n') next();
        }
        void skip_line()
        {
            match_until(is_lineend);
            skip_newline();
        }

        template<class Pred>
        StringView match_zero_or_more(Pred p)
        {
            const char* start = m_it.pointer_to_current();
            auto ch = cur();
            while (ch != Unicode::end_of_file && p(ch))
                ch = next();
            return {start, m_it.pointer_to_current()};
        }
        template<class Pred>
        StringView match_until(Pred p)
        {
            const char* start = m_it.pointer_to_current();
            auto ch = cur();
            while (ch != Unicode::end_of_file && !p(ch))
                ch = next();
            return {start, m_it.pointer_to_current()};
        }

        StringView text() const { return m_text; }
        Unicode::Utf8Decoder it() const { return m_it; }
        char32_t cur() const { return m_it == m_it.end() ? Unicode::end_of_file : *m_it; }
        SourceLoc cur_loc() const { return {m_it, m_start_of_line, m_row, m_column}; }
        TextRowCol cur_rowcol() const { return {m_row, m_column}; }
        char32_t next();
        bool at_eof() const { return m_it == m_it.end(); }

        void add_error(std::string message) { add_error(std::move(message), cur_loc()); }
        void add_error(std::string message, const SourceLoc& loc);

        const Parse::IParseError* get_error() const { return m_err.get(); }
        std::unique_ptr<Parse::IParseError> extract_error() { return std::move(m_err); }

    private:
        Unicode::Utf8Decoder m_it;
        Unicode::Utf8Decoder m_start_of_line;
        int m_row;
        int m_column;

        StringView m_text;
        StringView m_origin;

        std::unique_ptr<IParseError> m_err;
    };
}
