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

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

static const Pcre2Regex LogcatEntryRegex("^\\s*(\\d+)(?:\\.\\d+)?(?:\\s+([\\w\\d._-]+))?\\s+(\\d+)\\s+(\\d+)\\s+([A-Z])\\s+(.+?)\\s*:\\s(.*)$");
static const Pcre2Regex BufferRegex("^--------- (?:beginning of|switch to) (\\w+)$");

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;
    }
}

const char* priority_to(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";
        default: return "Unknown";
    }
}

const char* buffer_to(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";
        default: return "Unknown";
    }
}

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_unsigned_long_long(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;
}

std::optional<LogcatEntry> try_parse_logcat_entry(char* buf, size_t length, Buffer buffer) {
    regmatch_t matches[8];
    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;
    }

    std::optional<std::string> user;
    if (matches[2].rm_so > -1 && matches[2].rm_eo > -1) {
        user = std::string(&buf[matches[2].rm_so], static_cast<size_t>(matches[2].rm_eo - matches[2].rm_so));
    }
    // if pcre2 gives us negative offsets then i'll die
    LogcatEntry logcat_entry = {
        .buffer = buffer,
        .time = to_long(&buf[matches[1].rm_so], &buf[matches[1].rm_eo]),
        .user = std::move(user),
        .pid = to_unsigned_long_long(&buf[matches[3].rm_so], &buf[matches[3].rm_eo]),
        .tid = to_unsigned_long_long(&buf[matches[4].rm_so], &buf[matches[4].rm_eo]),
        .priority = priority_from(buf[matches[5].rm_so]),
        .tag = std::string(&buf[matches[6].rm_so], static_cast<size_t>(matches[6].rm_eo - matches[6].rm_so)),
        .message = std::string(&buf[matches[7].rm_so], static_cast<size_t>(matches[7].rm_eo - matches[7].rm_so)),
    };
    return std::move(logcat_entry);
}

static bool substr_equal(const char* lhs_str, size_t lhs_length, const char* rhs_str) {
    return lhs_length == strlen(rhs_str) && memcmp(lhs_str, rhs_str, lhs_length * sizeof(char)) == 0;
}

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];
    size_t buffer_length = static_cast<size_t>(matches[1].rm_eo - matches[1].rm_so);
    if (substr_equal(buffer_str, buffer_length, "main")) return Buffer::Main;
    if (substr_equal(buffer_str, buffer_length, "system")) return Buffer::System;
    if (substr_equal(buffer_str, buffer_length, "radio")) return Buffer::Radio;
    if (substr_equal(buffer_str, buffer_length, "events")) return Buffer::Events;
    if (substr_equal(buffer_str, buffer_length, "crash")) return Buffer::Crash;
    return Buffer::Unknown;
}