#include "mainwindow.h"
#include "ui_mainwindow.h"
#include "conversion.h"
#include <QClipboard>
#include <QApplication>

MainWindow::MainWindow(QWidget *parent)
    : QMainWindow(parent), ui(new Ui::MainWindow)
{
    ui->setupUi(this);
    ui->categoryCombo->addItems({tr("温度"), tr("长度")});
    connect(ui->categoryCombo, static_cast<void (QComboBox::*)(int)>(&QComboBox::currentIndexChanged),
            this, &MainWindow::changeCategory);
    connect(ui->convertButton, &QPushButton::clicked, this, &MainWindow::convertValue);
    connect(ui->inputEdit, &QLineEdit::returnPressed, this, &MainWindow::convertValue);
    connect(ui->inputEdit, &QLineEdit::textChanged, this, &MainWindow::clearResult);
    connect(ui->fromCombo, static_cast<void (QComboBox::*)(int)>(&QComboBox::currentIndexChanged),
            this, &MainWindow::clearResult);
    connect(ui->toCombo, static_cast<void (QComboBox::*)(int)>(&QComboBox::currentIndexChanged),
            this, &MainWindow::clearResult);
    connect(ui->swapButton, &QPushButton::clicked, this, [this] {
        const int previousFrom = ui->fromCombo->currentIndex();
        ui->fromCombo->setCurrentIndex(ui->toCombo->currentIndex());
        ui->toCombo->setCurrentIndex(previousFrom);
        ui->inputEdit->setFocus();
    });
    connect(ui->clearButton, &QPushButton::clicked, this, [this] {
        ui->inputEdit->clear();
        clearResult();
        ui->inputEdit->setFocus();
    });
    connect(ui->copyButton, &QPushButton::clicked, this, [this] {
        QApplication::clipboard()->setText(ui->resultEdit->text());
        ui->statusLabel->setText(tr("结果已复制。"));
    });
    changeCategory();
    ui->inputEdit->setText(QStringLiteral("25"));
}

MainWindow::~MainWindow() { delete ui; }

void MainWindow::changeCategory()
{
    const auto category = ui->categoryCombo->currentIndex() == 0
        ? Conversion::Category::Temperature : Conversion::Category::Length;
    const QStringList names = Conversion::units(category);
    ui->fromCombo->clear();
    ui->toCombo->clear();
    ui->fromCombo->addItems(names);
    ui->toCombo->addItems(names);
    ui->fromCombo->setCurrentIndex(category == Conversion::Category::Length ? 2 : 0);
    ui->toCombo->setCurrentIndex(1);
    clearResult();
}

void MainWindow::clearResult()
{
    ui->resultEdit->clear();
    ui->formulaLabel->setText(tr("选择单位并输入数值，点击“换算”查看计算过程。"));
    ui->statusLabel->clear();
    ui->copyButton->setEnabled(false);
}

void MainWindow::convertValue()
{
    const auto category = ui->categoryCombo->currentIndex() == 0
        ? Conversion::Category::Temperature : Conversion::Category::Length;
    const auto result = Conversion::convert(ui->inputEdit->text(), category,
                                            ui->fromCombo->currentIndex(),
                                            ui->toCombo->currentIndex());
    if (!result.ok) {
        clearResult();
        ui->statusLabel->setText(result.error);
        ui->inputEdit->setFocus();
        return;
    }
    ui->resultEdit->setText(QStringLiteral("%1 %2")
        .arg(result.value, 0, 'g', 12).arg(ui->toCombo->currentText()));
    ui->formulaLabel->setText(result.explanation);
    ui->statusLabel->setText(tr("换算完成。结果最多显示 12 位有效数字。"));
    ui->copyButton->setEnabled(true);
}