function showTab(tabId) {
    document.querySelectorAll('.tab-content').forEach(tab => {
        tab.classList.remove('active');
    });

    document.querySelectorAll('.subtab-content').forEach(subtab => {
        subtab.classList.remove('active');
    });

    const activeTab = document.getElementById(tabId);
    activeTab.classList.add('active');

    document.querySelectorAll('.tab').forEach(tab => {
        tab.classList.remove('active');
    });
    const activeTabElement = document.querySelector(`.tab[onclick*="${tabId}"]`);
    if (activeTabElement) {
        activeTabElement.classList.add('active');
    }

    const firstSubtab = activeTab.querySelector('.subtab-content');
    if (firstSubtab) {
        firstSubtab.classList.add('active');
        
    }
}

function showSubTab(subTabId) {
    document.querySelectorAll('.tab-content.active .subtab-content').forEach(subtab => {
        subtab.classList.remove('active');
    });

    const subtabToShow = document.getElementById(subTabId);
    subtabToShow.classList.add('active');

    document.querySelectorAll('.subtab').forEach(subtab => {
        subtab.classList.remove('active');
    });
    const activeSubtabElement = document.querySelector(`.subtab[onclick*="${subTabId}"]`);
    if (activeSubtabElement) {
        activeSubtabElement.classList.add('active');
    }

}

function importDataK1() {
    const fileInput = document.createElement("input");
    fileInput.type = "file";
    fileInput.accept = ".txt";
    fileInput.onchange = (event) => {
        const file = event.target.files[0];
        const reader = new FileReader();
        reader.onload = (e) => {
            const data = e.target.result.split('\n').map(line => line.trim());
            const dataTable = document.getElementById('dataTable').getElementsByTagName('tbody')[0];
            let rowIndex = 0;
            data.forEach((line, index) => {
                let row;
                if (rowIndex < dataTable.rows.length) {
                    row = dataTable.rows[rowIndex];
                } else {
                    row = dataTable.insertRow();
                    row.insertCell();
                    row.insertCell();
                }
                row.cells[0].textContent = line;
                rowIndex++;
            });
        };
        reader.readAsText(file);
    };

    fileInput.click();
}

function importDataK2() {
    const fileInput = document.createElement("input");
    fileInput.type = "file";
    fileInput.accept = ".txt";
    fileInput.onchange = (event) => {
        const file = event.target.files[0];
        const reader = new FileReader();
        reader.onload = (e) => {
            const data = e.target.result.split('\n').map(line => line.trim());
            const dataTable = document.getElementById('dataTable').getElementsByTagName('tbody')[0];
            let rowIndex = 0;
            data.forEach((line, index) => {
                let row;
                if (rowIndex < dataTable.rows.length) {
                    row = dataTable.rows[rowIndex];
                } else {
                    row = dataTable.insertRow();
                    row.insertCell();
                    row.insertCell();
                }

                row.cells[1].textContent = line;
                rowIndex++;
            });
        };
        reader.readAsText(file);
    };

    fileInput.click();
}

function importDataT1() {
    const fileInput = document.createElement("input");
    fileInput.type = "file";
    fileInput.accept = ".txt";
    fileInput.onchange = (event) => {
        const file = event.target.files[0];
        const reader = new FileReader();
        reader.onload = (e) => {
            const data = e.target.result.split('\n').map(line => line.trim());
            const dataTableTTest = document.getElementById('dataTableTTest').getElementsByTagName('tbody')[0];
            let rowIndex = 0;
            data.forEach((line, index) => {
                let row;
                if (rowIndex < dataTableTTest.rows.length) {
                    row = dataTableTTest.rows[rowIndex];
                } else {
                    row = dataTableTTest.insertRow();
                    row.insertCell();
                    row.insertCell();
                }

                row.cells[0].textContent = line;
                rowIndex++;
            });
        };
        reader.readAsText(file);
    };

    fileInput.click();
}

function importDataT2() {
    const fileInput = document.createElement("input");
    fileInput.type = "file";
    fileInput.accept = ".txt";
    fileInput.onchange = (event) => {
        const file = event.target.files[0];
        const reader = new FileReader();
        reader.onload = (e) => {
            const data = e.target.result.split('\n').map(line => line.trim());
            const dataTableTTest = document.getElementById('dataTableTTest').getElementsByTagName('tbody')[0];
            let rowIndex = 0;
            data.forEach((line, index) => {
                let row;
                if (rowIndex < dataTableTTest.rows.length) {
                    row = dataTableTTest.rows[rowIndex];
                } else {
                    row = dataTableTTest.insertRow();
                    row.insertCell();
                    row.insertCell();
                }

                row.cells[1].textContent = line;
                rowIndex++;
            });
        };
        reader.readAsText(file);
    };

    fileInput.click();
}

function importDataKC1() {
    const fileInput = document.createElement("input");
    fileInput.type = "file";
    fileInput.accept = ".txt";
    fileInput.onchange = (event) => {
        const file = event.target.files[0];
        const reader = new FileReader();
        reader.onload = (e) => {
            const data = e.target.result.split('\n').map(line => line.trim());
            const dataTable = document.getElementById('classesTable').getElementsByTagName('tbody')[0];
            let rowIndex = 0;
            data.forEach((line, index) => {
                let row;
                if (rowIndex < dataTable.rows.length) {
                    row = dataTable.rows[rowIndex];
                } else {
                    row = dataTable.insertRow();
                    row.insertCell();
                    row.insertCell();
                }

                row.cells[2].textContent = line;
                rowIndex++;
            });
        };
        reader.readAsText(file);
    };

    fileInput.click();
}

function importDataKC2() {
    const fileInput = document.createElement("input");
    fileInput.type = "file";
    fileInput.accept = ".txt";
    fileInput.onchange = (event) => {
        const file = event.target.files[0];
        const reader = new FileReader();
        reader.onload = (e) => {
            const data = e.target.result.split('\n').map(line => line.trim());
            const dataTable = document.getElementById('classesTable').getElementsByTagName('tbody')[0];
            let rowIndex = 0;
            data.forEach((line, index) => {
                let row;
                if (rowIndex < dataTable.rows.length) {
                    row = dataTable.rows[rowIndex];
                } else {
                    row = dataTable.insertRow();
                    row.insertCell();
                    row.insertCell();
                }

                row.cells[3].textContent = line;
                rowIndex++;
            });
        };
        reader.readAsText(file);
    };

    fileInput.click();
}

function importDataTC1() {
    const fileInput = document.createElement("input");
    fileInput.type = "file";
    fileInput.accept = ".txt";
    fileInput.onchange = (event) => {
        const file = event.target.files[0];
        const reader = new FileReader();
        reader.onload = (e) => {
            const data = e.target.result.split('\n').map(line => line.trim());
            const dataTableTTest = document.getElementById('classesTableTTest').getElementsByTagName('tbody')[0];
            let rowIndex = 0;
            data.forEach((line, index) => {
                let row;
                if (rowIndex < dataTableTTest.rows.length) {
                    row = dataTableTTest.rows[rowIndex];
                } else {
                    row = dataTableTTest.insertRow();
                    row.insertCell();
                    row.insertCell();
                }

                row.cells[2].textContent = line;
                rowIndex++;
            });
        };
        reader.readAsText(file);
    };

    fileInput.click();
}

function importDataTC2() {
    const fileInput = document.createElement("input");
    fileInput.type = "file";
    fileInput.accept = ".txt";
    fileInput.onchange = (event) => {
        const file = event.target.files[0];
        const reader = new FileReader();
        reader.onload = (e) => {
            const data = e.target.result.split('\n').map(line => line.trim());
            const dataTableTTest = document.getElementById('classesTableTTest').getElementsByTagName('tbody')[0];
            let rowIndex = 0;
            data.forEach((line, index) => {
                let row;
                if (rowIndex < dataTableTTest.rows.length) {
                    row = dataTableTTest.rows[rowIndex];
                } else {
                    row = dataTableTTest.insertRow();
                    row.insertCell();
                    row.insertCell();
                }

                row.cells[3].textContent = line;
                rowIndex++;
            });
        };
        reader.readAsText(file);
    };

    fileInput.click();
}


function clearTable() {
    const rows = document.querySelectorAll('#dataTable tbody tr');
    rows.forEach(row => {
        row.cells[0].innerText = '';
        row.cells[1].innerText = '';
    });
    const rowsTTest = document.querySelectorAll('#dataTableTTest tbody tr');
    rowsTTest.forEach(row => {
        row.cells[0].innerText = '';
        row.cells[1].innerText = '';
    });
}

document.querySelector('#dataTable tbody').addEventListener('keydown', function (e) {
    if (e.key === 'Enter') {
        e.preventDefault();
        const row = this.insertRow();
        row.innerHTML = `<td contenteditable="true"></td><td contenteditable="true"></td>`;
    }
});

function calculateKol() {
    const rows = document.querySelectorAll('#dataTable tbody tr');
    const freq1 = [];
    const freq2 = [];
    let n1 = 0;
    let n2 = 0;
    let a = 0;

    rows.forEach(row => {
        const cellValueA = parseFloat(row.cells[0].innerText) || 0;
        const cellValueB = parseFloat(row.cells[1].innerText) || 0;

        if ((!isNaN(cellValueA) && isNaN(cellValueB)) || (isNaN(cellValueA) && !isNaN(cellValueB))) {
            alert("Data entry error");
            return;
        }

        if (!isNaN(cellValueA) && !isNaN(cellValueB)) {
            freq1[a] = cellValueA;
            freq2[a] = cellValueB;
            a++;
        }
    });

    for (let i = 0; i < a; i++) {
        n1 += freq1[i];
        n2 += freq2[i];
    }

    if (a < 6 || n1 < 8 || n2 < 8) {
        alert("Insufficient data.");
        return;
    }

    const jval1 = new Array(a);
    const jval2 = new Array(a);
    jval1[0] = freq1[0] / n1;
    jval2[0] = freq2[0] / n2;

    for (let i = 1; i < a; i++) {
        jval1[i] = jval1[i - 1] + (freq1[i] / n1);
        jval2[i] = jval2[i - 1] + (freq2[i] / n2);
    }

    const DP = new Array(a);
    DP[0] = Math.abs(jval1[0] - jval2[0]);
    for (let i = 1; i < a; i++) {
        DP[i] = Math.abs(jval1[i] - jval2[i]);
    }

    const D = Math.max(...DP);
    document.getElementById('valueD').innerText = D.toFixed(3);

    const confidenceLevel = parseInt(document.getElementById('confidence').value);

    let criticalValue;
    const C1 = Math.sqrt((n1 + n2) / (n1 * n2));

    switch (confidenceLevel) {
        case 80:
            criticalValue = (1.28 * C1).toFixed(3);
            break;
        case 85:
            criticalValue = (1.34 * C1).toFixed(3);
            break;
        case 90:
            criticalValue = (1.22 * C1).toFixed(3);
            break;
        case 95:
            criticalValue = (1.36 * C1).toFixed(3);
            break;
        case 99:
            criticalValue = (1.63 * C1).toFixed(3);
            break;
        default:
            alert("Invalid confidence level selected.");
            return;
    }

    document.getElementById("criticalValue").textContent = criticalValue;

    const meanChangeMessage = document.getElementById("distChangeMessageKI");
    if (D < criticalValue) {
        meanChangeMessage.textContent = "The two distributions are not different";
    } else {
        meanChangeMessage.textContent = "The two distributions are different";
    }
}

function applyClasses() {
    const start = parseFloat(document.getElementById('startClass').value);
    const end = parseFloat(document.getElementById('endClass').value);
    const numClasses = parseInt(document.getElementById('numClasses').value);
    const classesTable = document.getElementById('classesTable');
    const classesBody = document.getElementById('classesBody');
    classesBody.innerHTML = '';

    if (numClasses > 0) {
        const interval = Math.abs(end - start) / numClasses;
        for (let i = 0; i < numClasses; i++) {
            let from, to;
            if (start < end) {
                from = (start + (i * interval)).toFixed(2);
                to = (start + ((i + 1) * interval)).toFixed(2);
            } else {
                from = (start - (i * interval)).toFixed(2);
                to = (start - ((i + 1) * interval)).toFixed(2);
            }
            const row = `<tr>
                            <td>${from}</td>
                            <td>${to}</td>
                            <td contenteditable="true"></td>
                            <td contenteditable="true"></td>
                         </tr>`;
            classesBody.innerHTML += row;
        }
        classesTable.style.display = 'table';
    }
}

function clearClasses() {
    document.getElementById('classesBody').innerHTML = '';
    document.getElementById('classesTable').style.display = 'none';
    document.getElementById('startClass').value = '';
    document.getElementById('endClass').value = '';
    document.getElementById('numClasses').value = '';
}

function calculateClasses() {
    const rows = document.querySelectorAll('#classesTable tbody tr');
    const freq1 = [];
    const freq2 = [];
    let n1 = 0;
    let n2 = 0;
    let a = 0;

    rows.forEach(row => {
        
        if (row.cells.length < 4) {
            return; 
        }

        const cellValueA = parseFloat(row.cells[2].innerText) || 0;
        const cellValueB = parseFloat(row.cells[3].innerText) || 0;

        if ((!isNaN(cellValueA) && isNaN(cellValueB)) || (isNaN(cellValueA) && !isNaN(cellValueB))) {
            alert("Data entry error");
            return;
        }

        if (!isNaN(cellValueA) && !isNaN(cellValueB)) {
            freq1[a] = cellValueA;
            freq2[a] = cellValueB;
            a++;
        }
    });

    for (let i = 0; i < a; i++) {
        n1 += freq1[i];
        n2 += freq2[i];
    }

    if (a < 6 || n1 < 8 || n2 < 8) {
        alert("Insufficient data.");
        return;
    }

    const jval1 = new Array(a);
    const jval2 = new Array(a);
    jval1[0] = freq1[0] / n1;
    jval2[0] = freq2[0] / n2;

    for (let i = 1; i < a; i++) {
        jval1[i] = jval1[i - 1] + (freq1[i] / n1);
        jval2[i] = jval2[i - 1] + (freq2[i] / n2);
    }

    const DP = new Array(a);
    DP[0] = Math.abs(jval1[0] - jval2[0]);
    for (let i = 1; i < a; i++) {
        DP[i] = Math.abs(jval1[i] - jval2[i]);
    }

    const D = Math.max(...DP);
    document.getElementById('valueDClasses').innerText = D.toFixed(3);

    const confidenceLevel = parseInt(document.getElementById('confidenceClasses').value);

    let criticalValue;
    const C1 = Math.sqrt((n1 + n2) / (n1 * n2));

    switch (confidenceLevel) {
        case 80:
            criticalValue = (1.28 * C1).toFixed(3);
            break;
        case 85:
            criticalValue = (1.34 * C1).toFixed(3);
            break;
        case 90:
            criticalValue = (1.22 * C1).toFixed(3);
            break;
        case 95:
            criticalValue = (1.36 * C1).toFixed(3);
            break;
        case 99:
            criticalValue = (1.63 * C1).toFixed(3);
            break;
        default:
            alert("Invalid confidence level selected.");
            return;
    }

    document.getElementById('criticalValueClasses').innerText = criticalValue;

    const meanChangeMessage = document.getElementById("distChangeMessageKC");
    if (D < criticalValue) {
        meanChangeMessage.textContent = "The two distributions are not different";
    } else {
        meanChangeMessage.textContent = "The two distributions are different";
    }
}

function calculateT() {
    const column1 = document.querySelectorAll("#dataTableTTest tr td:nth-child(2)");
    const column2 = document.querySelectorAll("#dataTableTTest tr td:nth-child(1)");
    let sum1 = 0, sum2 = 0, sumSq1 = 0, sumSq2 = 0;
    const n1 = column1.length;
    const n2 = column2.length;

    if (n1 === 0 || n2 === 0) {
        alert("Error: One of the data sets is empty.");
        return;
    }

    column1.forEach(cell => {
        const value = parseFloat(cell.textContent);
        if (!isNaN(value)) {
            sum1 += value;
            sumSq1 += value * value;
        } else {
            console.warn("Non-numeric value found in column 1:", cell.textContent);
        }
    });

    column2.forEach(cell => {
        const value = parseFloat(cell.textContent);
        if (!isNaN(value)) {
            sum2 += value;
            sumSq2 += value * value;
        } else {
            console.warn("Non-numeric value found in column 2:", cell.textContent);
        }
    });

    const mean1 = sum1 / n1;
    const mean2 = sum2 / n2;

    document.getElementById("meanDataSet1").textContent = mean1.toFixed(2);
    document.getElementById("meanDataSet2").textContent = mean2.toFixed(2);

    const sigma = Math.sqrt(((sumSq1 - (sum1 * sum1 / n1)) + (sumSq2 - (sum2 * sum2 / n2))) / (n1 + n2 - 2));
    
    if (isNaN(sigma) || sigma === 0) {
        alert("Error: Standard deviation calculation resulted in an invalid value.");
        return;
    }

    const tValue = (mean1 - mean2) / sigma * Math.sqrt((n1 * n2) / (n1 + n2));
    document.getElementById("tValue").textContent = tValue.toFixed(3);

    const degreesOfFreedom = n1 + n2 - 2;
    const confidenceSelect = document.getElementById("confidence_ttest");
    const confidenceLevel = parseFloat(confidenceSelect.value) / 100;

    const tCriticalValue = jStat.studentt.inv(1 - (1 - confidenceLevel) / 2, degreesOfFreedom);
    document.getElementById("tCriticalValue").textContent = tCriticalValue.toFixed(3);

    const labelT = document.getElementById("dynamicLabelTI");
    const alpha = (1 - confidenceLevel).toFixed(2);
    labelT.innerHTML = `t<sub>${degreesOfFreedom}, ${alpha}</sub>:`;

    const meanChangeMessage = document.getElementById("meanChangeMessageTI");
    if (tValue < tCriticalValue) {
        meanChangeMessage.textContent = "The mean has not changed";
    } else {
        meanChangeMessage.textContent = "The mean has changed";
    }
}

function applyClassesTTest() {
    const start = parseFloat(document.getElementById('startClassTTest').value);
    const end = parseFloat(document.getElementById('endClassTTest').value);
    const numClasses = parseInt(document.getElementById('numClassesTTest').value);
    const classesTableTTest = document.getElementById('classesTableTTest');
    const classesBodyTTest = document.getElementById('classesBodyTTest');
    classesBodyTTest.innerHTML = '';

    if (numClasses > 0) {
        const interval = Math.abs(end - start) / numClasses;
        let currentStart = start;
        let currentEnd = start;

        if (start < end) {
            currentEnd += interval;
        } else {
            currentEnd -= interval;
        }

        while ((start < end && currentEnd <= end) || (start >= end && currentEnd >= end)) {
            const row = `<tr>
                            <td>${currentStart.toFixed(2)}</td>
                            <td>${currentEnd.toFixed(2)}</td>
                            <td contenteditable="true"></td>
                            <td contenteditable="true"></td>
                         </tr>`;
            classesBodyTTest.innerHTML += row;
            currentStart = currentEnd;

            if (start < end) {
                currentEnd += interval;
            } else {
                currentEnd -= interval;
            }
        }

        classesTableTTest.style.display = 'table';
    }
}

function clearClassesTTest() {
    document.getElementById('classesBodyTTest').innerHTML = '';
    document.getElementById('classesTableTTest').style.display = 'none';
    document.getElementById('startClassTTest').value = '';
    document.getElementById('endClassTTest').value = '';
    document.getElementById('numClassesTTest').value = '';
}

function calculateClassesTTest() {
    const column1 = document.querySelectorAll("#classesTableTTest tr td:nth-child(4)");
    const column2 = document.querySelectorAll("#classesTableTTest tr td:nth-child(3)");

    let sum1 = 0, sum2 = 0, sumSq1 = 0, sumSq2 = 0;
    let n1 = column1.length, n2 = column2.length;

    column1.forEach(cell => {
        const value = parseFloat(cell.textContent);
        sum1 += value;
        sumSq1 += value * value;
    });

    column2.forEach(cell => {
        const value = parseFloat(cell.textContent);
        sum2 += value;
        sumSq2 += value * value;
    });

    const mean1 = sum1 / n1;
    const mean2 = sum2 / n2;

    document.getElementById("meanDataSetC1").textContent = mean2.toFixed(2);
    document.getElementById("meanDataSetC2").textContent = mean1.toFixed(2);

    const sigma = Math.sqrt(((sumSq1 - (sum1 * sum1 / n1)) + (sumSq2 - (sum2 * sum2 / n2))) / (n1 + n2 - 2));
    const tValue = (mean1 - mean2) / sigma * Math.sqrt((n1 * n2) / (n1 + n2));

    document.getElementById("tValueC").textContent = tValue.toFixed(3);

    const degreesOfFreedom = n1 + n2 - 2;
    const confidenceSelect = document.getElementById("confidenceClassesTTest");
    const confidenceLevel = parseFloat(confidenceSelect.value) / 100;

    const tCriticalValue = jStat.studentt.inv(1 - (1 - confidenceLevel) / 2, degreesOfFreedom);
    document.getElementById("tCriticalValueC").textContent = tCriticalValue.toFixed(3);

    const labelT = document.getElementById("dynamicLabelTC");
    const alpha = (1 - confidenceLevel).toFixed(2);
    labelT.innerHTML = `t<sub>${degreesOfFreedom}, ${alpha}</sub>:`;

    const meanChangeMessage = document.getElementById("meanChangeMessageTC");
    if (tValue < tCriticalValue) {
        meanChangeMessage.textContent = "The mean has not changed";
    } else {
        meanChangeMessage.textContent = "The mean has changed";
    }


}

function calculateSummaryT() {
    const nbS = parseFloat(document.getElementById("nbS").value);
    const sumBiS = parseFloat(document.getElementById("sumBiS").value);
    const sumBiSquaredS = parseFloat(document.getElementById("sumBiSquaredS").value);
    const naS = parseFloat(document.getElementById("naS").value);
    const sumAiS = parseFloat(document.getElementById("sumAiS").value);
    const sumAiSquaredS = parseFloat(document.getElementById("sumAiSquaredS").value);

    const meanDataSetS1 = sumBiS / nbS;
    const meanDataSetS2 = sumAiS / naS;

    document.getElementById("meanDataSetS1").textContent = meanDataSetS1.toFixed(2);
    document.getElementById("meanDataSetS2").textContent = meanDataSetS2.toFixed(2);

    const sigmaS = Math.sqrt(((sumAiSquaredS - (sumAiS ** 2) / naS) + (sumBiSquaredS - (sumBiS ** 2) / nbS)) / (naS + nbS - 2));
    const tS = ((meanDataSetS2 - meanDataSetS1) / sigmaS) * Math.sqrt((naS * nbS) / (naS + nbS));
    document.getElementById("tValueS").textContent = tS.toFixed(3);

    const degreesOfFreedomS = naS + nbS - 2;
    const confidenceSelectS = document.getElementById("confidenceSummary");
    const confidenceLevelS = parseFloat(confidenceSelectS.value) / 100;

    const tCriticalValueS = jStat.studentt.inv(1 - (1 - confidenceLevelS) / 2, degreesOfFreedomS);

    document.getElementById("tCriticalS").textContent = tCriticalValueS.toFixed(3);

    const labelT = document.getElementById("dynamicLabelT");
    const alpha = (1 - confidenceLevelS).toFixed(2);
    labelT.innerHTML = `t<sub>${degreesOfFreedomS}, ${alpha}</sub>:`;

    const meanChangeMessage = document.getElementById("meanChangeMessageS");
    if (tS < 0) {
        meanChangeMessage.textContent = "The mean has decreased";
    } else {
        meanChangeMessage.textContent = "The mean has increased";
    }
}