/* =======================================================================
   File: static/js/log_view.js
   Purpose:
       Log viewer functionality:
         - filtering
         - clearing
         - auto-scroll
         - delta polling (efficient)
         - rolling limit (prevent GUI freeze)
   ======================================================================= */

console.log(">>> log_view.js LOADING…");

/* ---------------------------------------------------------
   Log filtering
   --------------------------------------------------------- */
let LOG_FILTER = "ALL";
let LAST_LOG_INDEX = -1; // For delta polling
const MAX_LOG_LINES = 2000; // Rolling cap to prevent freezing

function applyLogFilter() {
  console.log(">>> log_view.js applyLogFilter(), filter =", LOG_FILTER);

  const lines = $$(".log-line");
  console.log(">>> log_view.js number of log-line elements:", lines.length);

  lines.forEach((line) => {
    const text = line.innerText;
    line.style.display =
      LOG_FILTER === "ALL" || text.includes(LOG_FILTER) ? "block" : "none";
  });
}

/* ---------------------------------------------------------
   UI bindings
   --------------------------------------------------------- */
document.addEventListener("DOMContentLoaded", () => {
  console.log(">>> log_view.js DOMContentLoaded");

  const filterSel = $("#log-filter");
  const clearBtn = $("#log-clear");
  const output = $("#log-output");

  if (!filterSel) {
    console.log(">>> log_view.js: No log viewer found on this page.");
    return;
  }

  console.log(">>> log_view.js: log viewer detected.");

  // Filter dropdown
  filterSel.addEventListener("change", () => {
    LOG_FILTER = filterSel.value;
    console.log(">>> log_view.js filter changed to:", LOG_FILTER);
    applyLogFilter();
  });

  // Clear log window
  if (clearBtn) {
    clearBtn.addEventListener("click", () => {
      console.log(">>> log_view.js log-clear clicked → clearing output");
      if (output) {
        output.innerHTML = "";
        LAST_LOG_INDEX = -1; // reset delta polling
      }
    });
  }
});

/* ---------------------------------------------------------
   Append + Rolling buffer
   --------------------------------------------------------- */
function logAppend(lineText) {
  const output = $("#log-output");
  if (!output) return;

  const div = document.createElement("div");
  div.classList.add("log-line");

  // -----------------------------------------------------
  // Assign subtype classes
  // -----------------------------------------------------
  if (lineText.includes("[DL]") || lineText.includes("[DOWNLOAD]")) {
    div.classList.add("dl");
  } else if (lineText.includes("[PARSE]")) {
    div.classList.add("parse");
  } else if (lineText.includes("[SAVE]")) {
    div.classList.add("save");
  } else if (lineText.includes("[AUDIO]")) {
    div.classList.add("audio");
  } else if (lineText.includes("[CTRL]")) {
    div.classList.add("ctrl");
  } else if (lineText.includes("[ERROR]")) {
    div.classList.add("error");
  } else {
    div.classList.add("default");
  }

  div.innerText = lineText;
  output.appendChild(div);

  // Rolling buffer
  while (output.children.length > MAX_LOG_LINES) {
    output.removeChild(output.firstChild);
  }

  applyLogFilter();
  autoScroll(output);
}

/* ---------------------------------------------------------
   Delta-based log polling
   --------------------------------------------------------- */
function pollLogs() {
  fetch(`/logs?last_index=${LAST_LOG_INDEX}`)
    .then((r) => r.json())
    .then((data) => {
      const lines = data.lines || [];
      if (lines.length > 0) {
        lines.forEach((line) => logAppend(line));
        LAST_LOG_INDEX = data.total - 1;
      }
    })
    .catch((err) => {
      console.warn(">>> log_view.js pollLogs() error:", err);
    });
}

// Poll every 800 ms
setInterval(pollLogs, 800);

console.log(">>> log_view.js LOADED");