// Copyright(c) 2017 YamaArashi
//
// Permission is hereby granted, free of charge, to any person obtaining a copy
// of this software and associated documentation files (the "Software"), to deal
// in the Software without restriction, including without limitation the rights
// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
// copies of the Software, and to permit persons to whom the Software is
// furnished to do so, subject to the following conditions:
//
// The above copyright notice and this permission notice shall be included in
// all copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
// THE SOFTWARE.

#include "c_file.h"

CFile::CFile(std::string path) {
    m_path = path;

    FILE* fp = std::fopen(path.c_str(), "rb");

    if (fp == NULL)
        fatal_error("Failed to open \"%s\" for reading.\n", path.c_str());

    std::fseek(fp, 0, SEEK_END);

    m_size = static_cast<size_t>(std::ftell(fp));

    m_buffer = new char[m_size + 1];
    m_buffer[m_size] = 0;

    std::rewind(fp);

    if (std::fread(m_buffer, m_size, 1, fp) != 1)
        fatal_error("Failed to read \"%s\".\n", path.c_str());

    std::fclose(fp);

    m_pos = 0;
    m_lineNum = 1;
}

CFile::~CFile() {
    delete[] m_buffer;
}

void CFile::FindIncbins() {
    char stringChar = 0;

    while (m_pos < m_size) {
        if (stringChar) {
            if (m_buffer[m_pos] == stringChar) {
                m_pos++;
                stringChar = 0;
            } else if (m_buffer[m_pos] == '\\' && m_buffer[m_pos + 1] == stringChar) {
                m_pos += 2;
            } else {
                if (m_buffer[m_pos] == '\n')
                    m_lineNum++;
                m_pos++;
            }
        } else {
            SkipWhitespace();
            CheckInclude();
            CheckIncbin();

            if (m_pos >= m_size)
                break;

            char c = m_buffer[m_pos++];

            if (c == '\n')
                m_lineNum++;
            else if (c == '"')
                stringChar = '"';
            else if (c == '\'')
                stringChar = '\'';
            else if (c == 0)
                fatal_error(INPUT_ERROR_MESSAGE("unexpected null character"));
        }
    }
}

bool CFile::ConsumeHorizontalWhitespace() {
    if (m_buffer[m_pos] == '\t' || m_buffer[m_pos] == ' ') {
        m_pos++;
        return true;
    }

    return false;
}

bool CFile::ConsumeNewline() {
    if (m_buffer[m_pos] == '\n') {
        m_pos++;
        m_lineNum++;
        return true;
    }

    if (m_buffer[m_pos] == '\r' && m_buffer[m_pos + 1] == '\n') {
        m_pos += 2;
        m_lineNum++;
        return true;
    }

    return false;
}

bool CFile::ConsumeComment() {
    if (m_buffer[m_pos] == '/' && m_buffer[m_pos + 1] == '*') {
        m_pos += 2;
        while (m_buffer[m_pos] != '*' || m_buffer[m_pos + 1] != '/') {
            if (m_buffer[m_pos] == 0)
                return false;
            if (!ConsumeNewline())
                m_pos++;
        }
        m_pos += 2;
        return true;
    } else if (m_buffer[m_pos] == '/' && m_buffer[m_pos + 1] == '/') {
        m_pos += 2;
        while (!ConsumeNewline()) {
            if (m_buffer[m_pos] == 0)
                return false;
            m_pos++;
        }
        return true;
    }

    return false;
}

void CFile::SkipWhitespace() {
    while (ConsumeHorizontalWhitespace() || ConsumeNewline() || ConsumeComment())
        ;
}

bool CFile::CheckIdentifier(const std::string& ident) {
    unsigned int i;

    for (i = 0; i < ident.length() && m_pos + i < m_size; i++)
        if (ident[i] != m_buffer[m_pos + i])
            return false;

    return (i == ident.length());
}

void CFile::CheckInclude() {
    if (m_buffer[m_pos] != '#')
        return;

    std::string ident = "#include";

    if (!CheckIdentifier(ident)) {
        return;
    }

    m_pos += ident.length();

    ConsumeHorizontalWhitespace();

    std::string path = ReadPath();

    if (!path.empty()) {
        m_includes.emplace(path);
    }
}

void CFile::CheckIncbin() {
    // Optimization: assume most lines are not incbins
    if (!(m_buffer[m_pos + 0] == 'I' && m_buffer[m_pos + 1] == 'N' && m_buffer[m_pos + 2] == 'C' &&
          m_buffer[m_pos + 3] == 'B' && m_buffer[m_pos + 4] == 'I' && m_buffer[m_pos + 5] == 'N' &&
          m_buffer[m_pos + 6] == '_')) {
        return;
    }

    std::string idents[6] = { "INCBIN_S8", "INCBIN_U8", "INCBIN_S16", "INCBIN_U16", "INCBIN_S32", "INCBIN_U32" };
    int incbinType = -1;

    for (int i = 0; i < 6; i++) {
        if (CheckIdentifier(idents[i])) {
            incbinType = i;
            break;
        }
    }

    if (incbinType == -1)
        return;

    auto oldPos = m_pos;
    auto oldLineNum = m_lineNum;

    m_pos += idents[incbinType].length();

    SkipWhitespace();

    if (m_buffer[m_pos] != '(') {
        m_pos = oldPos;
        m_lineNum = oldLineNum;
        return;
    }

    m_pos++;

    while (true) {
        SkipWhitespace();

        std::string path = ReadPath();

        SkipWhitespace();

        m_incbins.emplace(path);

        if (m_buffer[m_pos] != ',')
            break;

        m_pos++;
    }

    if (m_buffer[m_pos] != ')')
        fatal_error(INPUT_ERROR_MESSAGE("expected ')'"));

    m_pos++;
}

std::string CFile::ReadPath() {
    if (m_buffer[m_pos] != '"') {
        if (m_buffer[m_pos] == '<') {
            return std::string();
        }
        fatal_error(INPUT_ERROR_MESSAGE("expected '\"' or '<'"));
    }

    m_pos++;

    auto startPos = m_pos;

    while (m_buffer[m_pos] != '"') {
        if (m_buffer[m_pos] == 0) {
            if (m_pos >= m_size)
                fatal_error(INPUT_ERROR_MESSAGE("unexpected EOF in path string"));
            else
                fatal_error(INPUT_ERROR_MESSAGE("unexpected null character in path string"));
        }

        if (m_buffer[m_pos] == '\r' || m_buffer[m_pos] == '\n')
            fatal_error(INPUT_ERROR_MESSAGE("unexpected end of line character in path string"));

        if (m_buffer[m_pos] == '\\')
            fatal_error(INPUT_ERROR_MESSAGE("unexpected escape in path string"));

        m_pos++;
    }

    m_pos++;

    return std::string(m_buffer + startPos, m_pos - 1 - startPos);
}
