#include "check_runner.h"
#include <yql/essentials/sql/v1/format/sql_format.h>
#include <util/string/builder.h>

namespace NYql {
namespace NFastCheck {

namespace {

constexpr size_t FormatContextLimit = 100;

class TFormatRunner : public ICheckRunner {
public:
    TString GetCheckName() const final {
        return "format";
    }

    TCheckResponse Run(const TChecksRequest& request) final {
        switch (request.Syntax) {
        case ESyntax::SExpr:
            return RunSExpr(request);
        case ESyntax::PG:
            return RunPg(request);
        case ESyntax::YQL:
            return RunYql(request);
        }
    }

private:
    TCheckResponse RunSExpr(const TChecksRequest& request) {
        Y_UNUSED(request);
        // no separate check for format here
        return TCheckResponse{.CheckName = GetCheckName(), .Success = true};
    }

    TCheckResponse RunPg(const TChecksRequest& request) {
        Y_UNUSED(request);
        // no separate check for format here
        return TCheckResponse{.CheckName = GetCheckName(), .Success = true};
    }

    TCheckResponse RunYql(const TChecksRequest& request) {
        TCheckResponse res {.CheckName = GetCheckName()};
        if (request.SyntaxVersion != 1) {
            res.Issues.AddIssue(TIssue({}, "Only SyntaxVersion 1 is supported"));
            return res;
        }

        google::protobuf::Arena arena;
        NSQLTranslation::TTranslationSettings settings;
        settings.Arena = &arena;
        settings.File = request.File;
        settings.Antlr4Parser = true;
        settings.AnsiLexer = request.IsAnsiLexer;

        auto formatter = NSQLFormat::MakeSqlFormatter(settings);
        NYql::TIssues issues;
        TString formattedQuery;
        res.Success = formatter->Format(request.Program, formattedQuery, issues);
        if (res.Success && formattedQuery != request.Program) {
            res.Success = false;
            TPosition origPos(0, 1, request.File);
            TTextWalker origWalker(origPos, true);
            size_t i = 0;
            for (; i < Min(request.Program.size(), formattedQuery.size()); ++i) {
                if (request.Program[i] == formattedQuery[i]) {
                    origWalker.Advance(request.Program[i]);
                    continue;
                }

                while (i > 0 && TTextWalker::IsUtf8Intermediate(request.Program[i])) {
                    --i;
                }

                break;
            }

            TString formattedSample = formattedQuery.substr(i, FormatContextLimit);
            while (!formattedSample.empty() && TTextWalker::IsUtf8Intermediate(formattedQuery.back())) {
                formattedSample.erase(formattedSample.size() - 1);
            }

            TString origSample = request.Program.substr(i, FormatContextLimit);
            while (!origSample.empty() && TTextWalker::IsUtf8Intermediate(origSample.back())) {
                origSample.erase(origSample.size() - 1);
            }

            res.Issues.AddIssue(TIssue(origPos, TStringBuilder() <<
                "Format mismatch, expected:\n" << formattedSample << "\nbut got:\n" << origSample));
        }

        return res;
    }
};

}

std::unique_ptr<ICheckRunner> MakeFormatRunner() {
    return std::make_unique<TFormatRunner>();
}

}
}