#include <climits>
#include <cstring>
#include <optional>
#include <stdexcept>

#include "config.h"
#include "logcat_entry.h"
#include "pcre2_wrapper.h"

static const Pcre2Regex LogcatEntryRegex(
    "^ *(?:(\\d+)|(\\d{4,})-(\\d{2})-(\\d{2}) (\\d{2}):(\\d{2}):(\\d{2}))(?:\\.\\d+)?" // time and date
    "(?: +([\\w\\d._-]+))?" // optional user
    " +(\\d+)" // pid
    " +(\\d+)" // tid
    " +([A-Z])" // priority
    " +(.+?) *: (.*)$" // tag and message
);
static const Pcre2Regex BufferRegex("^--------- (?:beginning of|switch to) (\\w+)$");

static std::string leftpad(const std::string& str, size_t characters);
static inline char to_char(Priority priority);
static inline std::string rightpad(const std::string& str, size_t characters);

static inline Priority priority_from(char c);
static inline int to_int(const char* str, const char* expected_end);
static inline long to_long(const char* str, const char* expected_end);
static unsigned long long to_ull(const char* str, const char* expected_end);

const char* to_string(Priority priority) {
    switch (priority) {
        case Priority::Verbose: return "Verbose";
        case Priority::Debug: return "Debug";
        case Priority::Info: return "Info";
        case Priority::Warn: return "Warning";
        case Priority::Error: return "Error";
        case Priority::Fatal: return "Fatal";
        case Priority::Unknown: return "Unknown";
    }
    return "Unknown??";
}

const char* to_string(Buffer buffer) {
    switch (buffer) {
        case Buffer::Main: return "Main";
        case Buffer::System: return "System";
        case Buffer::Radio: return "Radio";
        case Buffer::Events: return "Events";
        case Buffer::Crash: return "Crash";
        case Buffer::Unknown: return "Unknown";
    }
    return "Unknown??";
}

const char* to_string_lower(Buffer buffer) {
    switch (buffer) {
        case Buffer::Main: return "main";
        case Buffer::System: return "system";
        case Buffer::Radio: return "radio";
        case Buffer::Events: return "events";
        case Buffer::Crash: return "crash";
        case Buffer::Unknown: return "unknown";
    }
    return "Unknown??";
}

std::string to_string(const LogcatEntry& logcat_entry) {
    struct tm tm = logcat_entry.time;
    time_t time = mktime(&tm);
    gmtime_r(&time, &tm);

    char logcat_style_time_as_str[32] = {0};
    strftime(logcat_style_time_as_str, 31 * sizeof(char), "%Y-%m-%d %H:%M:%S", &tm);

    return std::string(logcat_style_time_as_str)
        + ' ' + leftpad(logcat_entry.user.value_or("     "), 5)
        + ' ' + leftpad(std::to_string(logcat_entry.pid), 5)
        + ' ' + leftpad(std::to_string(logcat_entry.tid), 5)
        + ' ' + to_char(logcat_entry.priority)
        + ' ' + rightpad(logcat_entry.tag, 5)
        + ": " + logcat_entry.message;
}


std::optional<LogcatEntry> try_parse_logcat_entry(char* buf, size_t length, Buffer buffer) {
    regmatch_t matches[14];
    matches[0].rm_so = 0;
    matches[0].rm_eo = static_cast<regoff_t>(length);
    if (static_cast<size_t>(matches[0].rm_eo) != length) {
        throw std::range_error("Logcat entry line too long for int");
    }

    if (!LogcatEntryRegex.match(buf, sizeof(matches) / sizeof(regmatch_t), matches, REG_STARTEND)) {
        return std::nullopt;
    }

    auto group_exists = [](const regmatch_t& match) { return match.rm_so > -1 && match.rm_eo > -1; };
    auto group_int = [&](const regmatch_t& match) { return to_int(&buf[match.rm_so], &buf[match.rm_eo]); };
    auto group_long = [&](const regmatch_t& match) { return to_long(&buf[match.rm_so], &buf[match.rm_eo]); };
    auto group_ull = [&](const regmatch_t& match) { return to_ull(&buf[match.rm_so], &buf[match.rm_eo]); };
    auto group_string = [&](const regmatch_t& match) { return std::string(&buf[match.rm_so], static_cast<size_t>(match.rm_eo - match.rm_so)); };
    auto group_priority = [&](const regmatch_t& match) { return priority_from(buf[match.rm_so]); };

    // if pcre2 gives us negative offsets then i'll die
    LogcatEntry logcat_entry = {
        .buffer   = buffer,
        // time to be set later
        .user     = group_exists(matches[8]) ? std::optional(group_string(matches[8])) : std::nullopt,
        .pid      = group_ull(matches[9]),
        .tid      = group_ull(matches[10]),
        .priority = group_priority(matches[11]),
        .tag      = group_string(matches[12]),
        .message  = group_string(matches[13]),
    };

    if (group_exists(matches[1])) {
        time_t time = group_long(matches[1]);
        localtime_r(&time, &logcat_entry.time);
    } else {
        struct tm tm = {
            .tm_sec = group_int(matches[7]),
            .tm_min = group_int(matches[6]),
            .tm_hour = group_int(matches[5]),
            .tm_mday = group_int(matches[4]),
            .tm_mon = group_int(matches[3]),
            .tm_year = group_int(matches[2]) - 1900,
            .tm_isdst = -1,
            .tm_gmtoff = 0,
        };
        time_t time = mktime(&tm) + tm.tm_gmtoff; // for some reason you have to add the local time offset?
        localtime_r(&time, &logcat_entry.time);
    }

    return logcat_entry;
}

std::optional<Buffer> try_parse_buffer(char* buf, size_t length) {
    regmatch_t matches[2];
    matches[0].rm_so = 0;
    matches[0].rm_eo = static_cast<regoff_t>(length);
    if (static_cast<size_t>(matches[0].rm_eo) != length) {
        throw std::range_error("Buffer line too long for int");
    }

    if (!BufferRegex.match(buf, sizeof(matches) / sizeof(regmatch_t), matches, REG_STARTEND)) {
        return std::nullopt;
    }

    const char* buffer_str = &buf[matches[1].rm_so];
    if (!strncmp(buffer_str, "main", 4)) return Buffer::Main;
    if (!strncmp(buffer_str, "system", 6)) return Buffer::System;
    if (!strncmp(buffer_str, "radio", 5)) return Buffer::Radio;
    if (!strncmp(buffer_str, "events", 6)) return Buffer::Events;
    if (!strncmp(buffer_str, "crash", 5)) return Buffer::Crash;
    return Buffer::Unknown;
}


void LogcatEntries::push_back(LogcatEntry entry) {
    this->_logcat_entries.push_back(std::move(entry));
    if (matches(this->_logcat_entries.back(), this->_config.filters, this->_config.exclusions)) {
        this->_filtered_offsets.push_back(this->_logcat_entries.size() - 1);
    }
}

void LogcatEntries::refresh() {
    this->_filtered_offsets.clear();
    for (size_t i = 0; i < this->_logcat_entries.size(); i++) {
        if (matches(this->_logcat_entries[i], this->_config.filters, this->_config.exclusions)) {
            this->_filtered_offsets.push_back(i);
        }
    }
}


void from_json(const nlohmann::json& j, Buffer& buffer) {
    const std::string& str = j.get_ref<const nlohmann::json::string_t&>();

    if (str == "UNKNOWN") buffer = Buffer::Unknown;
    else if (str == "MAIN") buffer = Buffer::Main;
    else if (str == "SYSTEM") buffer = Buffer::System;
    else if (str == "RADIO") buffer = Buffer::Radio;
    else if (str == "EVENTS") buffer = Buffer::Events;
    else if (str == "CRASH") buffer = Buffer::Crash;
    else throw std::invalid_argument(std::string("Unknown buffer value: ") + str);
}

void to_json(nlohmann::json& j, const Buffer& buffer) {
    switch (buffer) {
        case Buffer::Unknown: j = "UNKNOWN"; break;
        case Buffer::Main: j = "MAIN"; break;
        case Buffer::System: j = "SYSTEM"; break;
        case Buffer::Radio: j = "RADIO"; break;
        case Buffer::Events: j = "EVENTS"; break;
        case Buffer::Crash: j = "CRASH"; break;
    }
}

void from_json(const nlohmann::json& j, Priority& priority) {
    const std::string& str = j.get_ref<const nlohmann::json::string_t&>();

    if (str == "UNKNOWN") priority = Priority::Unknown;
    else if (str == "VERBOSE") priority = Priority::Verbose;
    else if (str == "DEBUG") priority = Priority::Debug;
    else if (str == "INFO") priority = Priority::Info;
    else if (str == "WARN") priority = Priority::Warn;
    else if (str == "ERROR") priority = Priority::Error;
    else if (str == "FATAL") priority = Priority::Fatal;
    else throw std::invalid_argument(std::string("Unknown priority value: ") + str);
}

void to_json(nlohmann::json& j, const Priority& priority) {
    switch (priority) {
        case Priority::Unknown: j = "UNKNOWN"; break;
        case Priority::Verbose: j = "VERBOSE"; break;
        case Priority::Debug: j = "DEBUG"; break;
        case Priority::Info: j = "INFO"; break;
        case Priority::Warn: j = "WARN"; break;
        case Priority::Error: j = "ERROR"; break;
        case Priority::Fatal: j = "FATAL"; break;
    }
}


static std::string leftpad(const std::string& str, size_t characters) {
    return str.size() >= characters
        ? str
        : std::string(characters - str.size(), ' ') + str;
}

static inline char to_char(Priority priority) {
    switch (priority) {
        case Priority::Verbose: return 'V';
        case Priority::Debug: return 'D';
        case Priority::Info: return 'I';
        case Priority::Warn: return 'W';
        case Priority::Error: return 'E';
        case Priority::Fatal: return 'F';
        case Priority::Unknown: return 'U';
    }
    return 'U';
}

static inline std::string rightpad(const std::string& str, size_t characters) {
    return str.size() >= characters
        ? str
        : str + std::string(characters - str.size(), ' ');
}


static inline Priority priority_from(char c) {
    switch (c) {
        case 'V': return Priority::Verbose;
        case 'D': return Priority::Debug;
        case 'I': return Priority::Info;
        case 'W': return Priority::Warn;
        case 'E': return Priority::Error;
        case 'F': return Priority::Fatal;
        default: return Priority::Unknown;
    }
}

static inline int to_int(const char* str, const char* expected_end) {
    long res = to_long(str, expected_end);
    if (res > INT_MAX) {
        throw std::overflow_error(std::string(str) + " is too big");
    } else if (res < INT_MIN) {
        throw std::underflow_error(std::string(str) + " is too small");
    }
    return static_cast<int>(res);
}

static inline long to_long(const char* str, const char* expected_end) {
    char* endptr;

    errno = 0;
    long res = strtol(str, &endptr, 10);
    if (endptr != expected_end) {
        throw std::invalid_argument(std::string(str) + " has trailing text");
    } else if (res == LONG_MAX && errno == ERANGE) {
        throw std::overflow_error(std::string(str) + " is too big");
    } else if (res == LONG_MIN && errno == ERANGE) {
        throw std::underflow_error(std::string(str) + " is too small");
    }
    return res;
}

static unsigned long long to_ull(const char* str, const char* expected_end) {
    char* endptr;

    errno = 0;
    unsigned long long res = strtoull(str, &endptr, 10);
    if (endptr != expected_end) {
        throw std::invalid_argument(std::string(str) + " has trailing text");
    } else if (res == ULLONG_MAX && errno == ERANGE) {
        throw std::overflow_error(std::string(str) + " is too big");
    }
    return res;
}