#include "csv_reader.h"

#include <errno.h>
#include <limits.h>
#include <stdlib.h>

#include <algorithm>
#include <fstream>
#include <iostream>
#include <sstream>

using namespace std;


CSVField::CSVField(int start, int length, bool hasQuotes): start(start),
                                                           length(length),
                                                           hasQuotes(hasQuotes)
{
}

CSVRow::CSVRow(string *row,
               const std::string * const filePath,
               long lineNumber,
               char delimiter,
               char quote): m_row(row),
                            m_filePath(filePath),
                            m_lineNumber(lineNumber),
                            m_quote(quote)
{
    parse(delimiter, quote);
}

string CSVRow::toString() const {
    stringstream ss;

    ss << "CSVRow (" << endl;

    if (m_lineNumber > 0) {
        ss << "  line #: \"" << m_lineNumber << "\"" << endl;
    }

    if (m_filePath) {
        ss << "  path: \"" << *m_filePath << "\"" << endl;
    }

    ss << "  value: \"" << *m_row << "\"" << endl;

    for (unsigned int i = 0; i < m_fields.size(); i++) {
        string row;
        getFieldAsString(i, &row);
        ss << "  field " << i << ": '" << row << "'" << endl;
    }

    ss << ")";
    return ss.str();
}

static bool string_to_long(const string &s, long *out) {
    const char *cstr = s.c_str();
    char *end = NULL;

    errno = 0;

    long x = strtol(cstr, &end, 10);

    if (errno != 0) {
        return false;
    } else if (end == &cstr[s.size()]) {
        *out = x;
        return true;
    } else {
        return false;
    }
}

static bool cstring_to_long(const char *start, const char *end, long *out) {
    char *parse_end = NULL;

    errno = 0;

    long x = strtol(start, &parse_end, 10);

    if (errno != 0) {
        return false;
    } else if (parse_end == end) {
        *out = x;
        return true;
    } else {
        return false;
    }
}

static bool string_to_double(const string &s, double *out) {
    const char *cstr = s.c_str();
    char *end = NULL;

    errno = 0;

    double x = strtod(cstr, &end);

    if (errno != 0) {
        return false;
    } else if (end == &cstr[s.size()]) {
        *out = x;
        return true;
    } else {
        return false;
    }
}

static bool cstring_to_double(const char *start, const char *end, double *out) {
    char *parse_end = NULL;

    errno = 0;

    double x = strtod(start, &parse_end);

    if (errno != 0) {
        return false;
    } else if (parse_end == end) {
        *out = x;
        return true;
    } else {
        return false;
    }
}

bool CSVRow::getFieldAsString(unsigned int fieldIndex, string *out) const {
    if (fieldIndex < m_fields.size()) {
        CSVField field = m_fields[fieldIndex];

        if (field.length == 0) {
            *out = "";
        } else {
            string s;

            if (field.hasQuotes) {
                s = m_row->substr(field.start, field.length);
                s = unquote(s, m_quote);
            } else {
                s = m_row->substr(field.start, field.length);
            }

            // remove newlines
            s.erase(std::remove(s.begin(), s.end(), '\n'), s.end());
            s.erase(std::remove(s.begin(), s.end(), '\r'), s.end());

            *out = s;
        }

        return true;
    } else {
        return false;
    }
}

bool CSVRow::getFieldAsLong(unsigned int fieldIndex, long *out) const {
    if (fieldIndex >= m_fields.size()) {
        return false;
    }

    if (m_fields[fieldIndex].hasQuotes) {
        string field;
        if (!getFieldAsString(fieldIndex, &field)) {
            return false;
        }

        return string_to_long(field, out);
    } else {
        const CSVField *field = &m_fields[fieldIndex];
        int sep_index = field->start + field->length;
        char sep = (*m_row)[sep_index];
        (*m_row)[sep_index] = '\0';

        bool ok = cstring_to_long(m_row->c_str() + field->start, m_row->c_str() + sep_index, out);

        (*m_row)[sep_index] = sep;

        return ok;
    }
}

bool CSVRow::getFieldAsInt(unsigned int fieldIndex, int *out) const {
    if (fieldIndex >= m_fields.size()) {
        return false;
    }

    long x;
    if (!getFieldAsLong(fieldIndex, &x)) {
        return false;
    }

    if (x < INT_MIN || x > INT_MAX) {
        // underflow or overflow
        return false;
    }

    *out = (int)x;

    return true;
}

bool CSVRow::getFieldAsDouble(unsigned int fieldIndex, double *out) const {
    if (fieldIndex >= m_fields.size()) {
        return false;
    }

    if (m_fields[fieldIndex].hasQuotes) {
        string field;
        if (!getFieldAsString(fieldIndex, &field)) {
            return false;
        }

        return string_to_double(field, out);
    } else {
        const CSVField *field = &m_fields[fieldIndex];
        int sep_index = field->start + field->length;
        char sep = (*m_row)[sep_index];
        (*m_row)[sep_index] = '\0';

        bool ok = cstring_to_double(m_row->c_str() + field->start, m_row->c_str() + sep_index, out);

        (*m_row)[sep_index] = sep;

        return ok;
    }
}

string CSVRow::getFilePath() const {
    if (m_filePath) {
        return string(*m_filePath);
    } else {
        return "";
    }
}

long CSVRow::getLineNumber() const {
    return m_lineNumber;
}

unsigned int CSVRow::getNumberOfFields() const {
    return m_fields.size();
}

void CSVRow::parse(char delimiter, char quote) {
    m_fields.clear();

    //TODO: properly handle unicode strings (could use QString::fromUtf8 and iterate over that)
    int start = 0;
    int length = -1;
    bool in_quotes = false;
    bool has_quotes = false;

    unsigned int size = m_row->size();

    // handle trailing \n and \r chars
    while (size > 0 && ((*m_row)[size - 1] == '\n' || (*m_row)[size - 1] == '\r')) {
        size--;
    }

    for (unsigned int i = 0; i < size; i++) {
        length++;
        char c = (*m_row)[i];

        if (c == delimiter && !in_quotes) {
            m_fields.push_back(CSVField(start, length, has_quotes));
            start = i + 1;
            length = -1;
            has_quotes = false;
        }

        if (c == quote) {
            has_quotes = true;
            if (in_quotes) {
                in_quotes = false;
            } else {
                in_quotes = true;
            }
        }
    }
    if (!(start == 0 && length == -1)) {
        length++;
        m_fields.push_back(CSVField(start, length, has_quotes));
    }
}

string CSVRow::unquote(const string &fieldStr, char quoteChar) {
    string ret;
    bool in_quotes = false;
    bool last_char_was_quote = false;

    //TODO: properly handle unicode strings here too
    for (unsigned int i = 0; i < fieldStr.size(); i++) {
        char c = fieldStr[i];

        if (in_quotes) {
            if (c == quoteChar) {
                in_quotes = false;
                last_char_was_quote = true;
            } else {
                ret.push_back(c);
                last_char_was_quote = false;
            }
        } else {
            if (c == quoteChar) {
                in_quotes = true;
                if (last_char_was_quote) {
                    ret.push_back(quoteChar);
                }
            }
            last_char_was_quote = false;
        }
    }

    return ret;
}

string CSVRow::quote(const string &fieldStr, char quoteChar) {
    string ret;

    //TODO: properly handle unicode strings here too
    //TODO: optimize using string::find
    for (unsigned int i = 0; i < fieldStr.size(); i++) {
        char c = fieldStr[i];

        if (c == quoteChar) {
            ret.append(2, quoteChar);
        } else {
            ret.push_back(c);
        }
    }

    return ret;
}

bool CSVReader::readFromFile(const std::string filePath,
                             CSVReader::RowCallback callback,
                             void *userData,
                             char delimiter,
                             char quote)
{
    ifstream stream;
    stream.open(filePath.c_str(), ios::in);
    if (stream) {
        bool ok = CSVReader::readFromStream(stream,
                                            callback,
                                            userData,
                                            &filePath,
                                            delimiter,
                                            quote);
        stream.close();
        return ok;
    } else {
        cerr << "Error: Cannot read file \"" << filePath << "\"" << endl;
        return false;
    }

    return true;
}


bool CSVReader::readFromStream(std::istream &stream,
                               CSVReader::RowCallback callback,
                               void *userData,
                               const string * const filePath,
                               char delimiter,
                               char quote)
{
    string line = "";
    long nr = 0;
    while (getline(stream, line, '\n')) {
        nr++;
        if (line.size() > 0) {
            CSVRow row(&line, filePath, nr, delimiter, quote);
            if (!callback(row, userData)) {
                return false;
            }
        }
    }

    return true;
}