<!DOCTYPE html>
<html th:lang="${#locale.language}" th:lang-direction="#{language.direction}" th:language="${#locale.toString()}" xmlns:th="http://www.thymeleaf.org">
  <head>
  <th:block th:insert="~{fragments/common :: head(title=#{compare.title}, header=#{compare.header})}"></th:block>
    <style>
      .result-column {
        border: 1px solid #ccc;
        padding: 15px;
        overflow-y: auto;
        height: calc(100vh - 400px);
        white-space: pre-wrap;
      }
    </style>
  </head>

  <body>
    <div id="page-container">
      <div id="content-wrap">
        <th:block th:insert="~{fragments/navbar.html :: navbar}"></th:block>
        <br /><br />
        <div class="container">
          <div class="row justify-content-center">
            <div class="col-md-9">
              <h2 th:text="#{compare.header}"></h2>
              <div th:replace="~{fragments/common :: fileSelector(name='fileInput', multiple=false, accept='application/pdf', remoteCall='false')}"></div>
              <div th:replace="~{fragments/common :: fileSelector(name='fileInput2', multiple=false, accept='application/pdf', remoteCall='false')}"></div>
              <button class="btn btn-primary"  onclick="comparePDFs()" th:text="#{compare.submit}"></button>
              <div class="row">
                <div class="col-md-6">
                  <h3 th:text="#{compare.document.1}"></h3>
                  <div id="result1" class="result-column"></div>
                </div>
                <div class="col-md-6">
                  <h3 th:text="#{compare.document.2}"></h3>
                  <div id="result2" class="result-column"></div>
                </div>
              </div>
              <script>
                // get the elements
                var result1 = document.getElementById('result1');
                var result2 = document.getElementById('result2');

                // add event listeners
                result1.addEventListener('scroll', function() {
                  result2.scrollTop = result1.scrollTop;
                });

                result2.addEventListener('scroll', function() {
                  result1.scrollTop = result2.scrollTop;
                });

                async function comparePDFs() {
                  const file1 = document.getElementById("fileInput-input").files[0];
                  const file2 = document.getElementById("fileInput2-input").files[0];

                  if (!file1 || !file2) {
                    console.error("Please select two PDF files to compare");
                    return;
                  }
                  pdfjsLib.GlobalWorkerOptions.workerSrc = 'pdfjs/pdf.worker.js'
                  const [pdf1, pdf2] = await Promise.all([
                    pdfjsLib.getDocument(URL.createObjectURL(file1)).promise,
                    pdfjsLib.getDocument(URL.createObjectURL(file2)).promise
                  ]);

                  const extractText = async (pdf) => {
                    const pages = [];
                    for (let i = 1; i <= pdf.numPages; i++) {
                      const page = await pdf.getPage(i);
                      const content = await page.getTextContent();
                      const strings = content.items.map(item => item.str);
                      pages.push(strings.join(" "));
                    }
                    return pages.join(" ");
                  };

                  const [text1, text2] = await Promise.all([
                    extractText(pdf1),
                    extractText(pdf2)
                  ]);

                  if (text1.trim() === "" || text2.trim() === "") {
                    alert("One or both of the selected PDFs have no text content. Please choose PDFs with text for comparison.");
                    return;
                  }
                  const diff = (text1, text2) => {
                    const words1 = text1.split(' ');
                    const words2 = text2.split(' ');

                    // Create a 2D array to hold our "matrix"
                    const matrix = Array(words1.length + 1).fill(null).map(() => Array(words2.length + 1).fill(0));

                    // Perform standard LCS algorithm
                    for (let i = 1; i <= words1.length; i++) {
                      for (let j = 1; j <= words2.length; j++) {
                        if (words1[i - 1] === words2[j - 1]) {
                          matrix[i][j] = matrix[i - 1][j - 1] + 1;
                        } else {
                          matrix[i][j] = Math.max(matrix[i][j - 1], matrix[i - 1][j]);
                        }
                      }
                    }

                    let i = words1.length;
                    let j = words2.length;
                    const differences = [];

                    // Backtrack through the matrix to create the diff
                    while (i > 0 || j > 0) {
                      if (i > 0 && j > 0 && words1[i - 1] === words2[j - 1]) {
                        differences.unshift(['black', words1[i - 1]]);
                        i--;
                        j--;
                      } else if (j > 0 && (i === 0 || matrix[i][j - 1] >= matrix[i - 1][j])) {
                        differences.unshift(['green', words2[j - 1]]);
                        j--;
                      } else if (i > 0 && (j === 0 || matrix[i][j - 1] < matrix[i - 1][j])) {
                        differences.unshift(['red', words1[i - 1]]);
                        i--;
                      }
                    }

                    return differences;
                  };

                  const differences = diff(text1, text2);

                  const displayDifferences = (differences) => {
                    const resultDiv1 = document.getElementById("result1");
                    const resultDiv2 = document.getElementById("result2");
                    resultDiv1.innerHTML = "";
                    resultDiv2.innerHTML = "";

                    differences.forEach(([color, word]) => {
                      const span1 = document.createElement("span");
                      const span2 = document.createElement("span");

                      // If it's an addition, show it in green in the second document and transparent in the first
                      if (color === "green") {
                        span1.style.color = "transparent";
                        span1.style.userSelect = "none";
                        span2.style.color = color;
                      }
                      // If it's a deletion, show it in red in the first document and transparent in the second
                      else if (color === "red") {
                        span1.style.color = color;
                        span2.style.color = "transparent";
                        span2.style.userSelect = "none";
                      }
                      // If it's unchanged, show it in black in both
                      else {
                        span1.style.color = color;
                        span2.style.color = color;
                      }

                      span1.textContent = word;
                      span2.textContent = word;
                      resultDiv1.appendChild(span1);
                      resultDiv2.appendChild(span2);

                      // Add space after each word, or a new line if the word ends with a full stop
                      const spaceOrNewline1 = document.createElement("span");
                      const spaceOrNewline2 = document.createElement("span");
                      if (word.endsWith(".")) {
                        spaceOrNewline1.innerHTML = "<br>";
                        spaceOrNewline2.innerHTML = "<br>";
                      } else {
                        spaceOrNewline1.textContent = " ";
                        spaceOrNewline2.textContent = " ";
                      }
                      resultDiv1.appendChild(spaceOrNewline1);
                      resultDiv2.appendChild(spaceOrNewline2);
                    });
                  };

                  console.log('Differences:', differences);
                  displayDifferences(differences);
                }
              </script>
            </div>
          </div>
        </div>
      </div>
      <th:block th:insert="~{fragments/footer.html :: footer}"></th:block>
    </div>
  </body>
</html>
