/*
 * Copyright 2021 Google LLC
 *
 * Use of this source code is governed by a BSD-style license that can be
 * found in the LICENSE file.
 */

#ifndef SKSL_POSITION
#define SKSL_POSITION

#include "include/core/SkTypes.h"

#include <cstdint>
#include <string_view>

namespace SkSL {

class Position {
public:
    Position()
        : fStartOffset(-1)
        , fLength(0) {}

    static Position Range(int startOffset, int endOffset) {
        SkASSERT(startOffset <= endOffset);
        SkASSERT(startOffset <= kMaxOffset);
        int length = endOffset - startOffset;
        Position result;
        result.fStartOffset = startOffset;
        result.fLength = length <= 0xFF ? length : 0xFF;
        return result;
    }

    bool valid() const {
        return fStartOffset != -1;
    }

    int line(std::string_view source) const;

    int startOffset() const {
        SkASSERT(this->valid());
        return fStartOffset;
    }

    int endOffset() const {
        SkASSERT(this->valid());
        return fStartOffset + fLength;
    }

    // Returns the position from this through, and including the entirety of, end.
    Position rangeThrough(Position end) const {
        if (fStartOffset == -1 || end.fStartOffset == -1) {
            return *this;
        }
        SkASSERTF(this->startOffset() <= end.startOffset() && this->endOffset() <= end.endOffset(),
                "Invalid range: (%d-%d) - (%d-%d)\n", this->startOffset(), this->endOffset(),
                end.startOffset(), end.endOffset());
        return Range(this->startOffset(), end.endOffset());
    }

    // Returns a position representing the character immediately after this position
    Position after() const {
        int endOffset = this->endOffset();
        return Range(endOffset, endOffset + 1);
    }

    bool operator==(const Position& other) const {
        return fStartOffset == other.fStartOffset && fLength == other.fLength;
    }

    bool operator!=(const Position& other) const {
        return !(*this == other);
    }

    bool operator>(const Position& other) const {
        return fStartOffset > other.fStartOffset;
    }

    bool operator>=(const Position& other) const {
        return fStartOffset >= other.fStartOffset;
    }

    bool operator<(const Position& other) const {
        return fStartOffset < other.fStartOffset;
    }

    bool operator<=(const Position& other) const {
        return fStartOffset <= other.fStartOffset;
    }

    static constexpr int kMaxOffset = 0x7FFFFF;

private:
    int32_t fStartOffset : 24;
    uint32_t fLength : 8;
};

struct ForLoopPositions {
    Position initPosition = Position();
    Position conditionPosition = Position();
    Position nextPosition = Position();
};

} // namespace SkSL

#endif
