/* =======================================================================
   File: static/js/log_view.js
   Purpose:
       High-performance rolling log viewer
       - efficient delta polling
       - append-only mode (no DOM reset)
       - rolling limit (prevents memory freeze)
       - supports both global logs and per-book logs
   ======================================================================= */

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

/* ---------------------------------------------------------
   Global log viewer state
   --------------------------------------------------------- */
let LOG_FILTER = "ALL";
let LAST_LOG_INDEX = -1; // delta offset
const MAX_LOG_LINES = 600; // safe rolling window

/* ---------------------------------------------------------
   Apply filter on existing log lines
   --------------------------------------------------------- */
function applyLogFilter() {
  const lines = $$(".log-line");
  lines.forEach((line) => {
    const text = line.innerText;
    const show = LOG_FILTER === "ALL" || (text && text.includes(LOG_FILTER));
    line.style.display = show ? "block" : "none";
  });
}

/* ---------------------------------------------------------
   DOM Ready — bind clear/filter
   --------------------------------------------------------- */
document.addEventListener("DOMContentLoaded", () => {
  console.log(">>> log_view.js DOMContentLoaded");

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

  if (!output) {
    console.log(
      ">>> log_view.js: No #log-output on this page → viewer disabled"
    );
    return;
  }

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

  // Filter dropdown (currently disabled in your UI)
  // if (filterSel) {
  //   filterSel.addEventListener("change", () => {
  //     LOG_FILTER = filterSel.value;
  //     applyLogFilter();
  //   });
  // }

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

/* ---------------------------------------------------------
   Append ONE line (smart class assignment)
   --------------------------------------------------------- */
function rollingAppend(lineText) {
  const output = $("#log-output");
  if (!output) return;

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

  // Type detection
  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.textContent = lineText;

  output.appendChild(div);

  // Rolling limit
  while (output.childNodes.length > MAX_LOG_LINES) {
    output.removeChild(output.firstChild);
  }
}

/* ---------------------------------------------------------
   Primary API entry: updateLogs()
   Used by dashboard.js AND delta polling
   Accepts:
     { logs: [...], last_index: N }
     OR legacy:
     { lines: [...], total: N }
   --------------------------------------------------------- */
function updateLogs(packet) {
  const output = $("#log-output");
  if (!output) return;

  if (!packet) return;

  // Normalized log arrays
  let lines = packet.logs || packet.lines || [];
  if (!Array.isArray(lines)) return;

  // Append only new lines
  lines.forEach((line) => rollingAppend(line));

  // Update delta index
  if (packet.last_index !== undefined) {
    LAST_LOG_INDEX = packet.last_index;
  } else if (packet.total !== undefined) {
    LAST_LOG_INDEX = packet.total - 1;
  }

  applyLogFilter();
  autoScroll(output);
}

/* ---------------------------------------------------------
   Delta polling: ONLY global logs use this
   Dashboard overrides logs per book.
   --------------------------------------------------------- */
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.last; // <-- DE JUISTE INDEX!
      }
    })
    .catch((err) => {
      console.warn(">>> log_view.js pollLogs() error:", err);
    });
}

setInterval(pollLogs, 2800);

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