// editor.js — Phase 1 of editable-cell mode.
//
// Owns the cell-selection + per-cell edit lifecycle. Implements the
// W3C ARIA grid-pattern keyboard semantics:
//
//   - Arrow keys move the selected cell.
//   - Tab / Shift-Tab move right / left, wrapping to next / prev row.
//   - Enter, F2, double-click, or any printable character enter edit
//     mode (Enter and F2 keep the existing value; printable chars
//     replace it; double-click opens with the existing value).
//   - In edit mode: Enter commits and moves down, Tab commits and
//     moves right, Escape cancels (restoring the prior value), blur
//     commits.
//
// Roving tabindex: only the selected cell carries tabindex=0; all
// others are tabindex=-1. This makes the grid a single tab-stop in
// the page's tab order, which is the documented spreadsheet UX.
//
// Edits in this phase live in app.state.drafts and never hit the
// network — Phase 3 wires the row-blur PUT.
(function (app) {
    'use strict';

    // --- Helpers ------------------------------------------------------

    function tableEl()    { return document.getElementById('table-root'); }
    function cellAt(r, c) { return cellsByRowCol(r, c); }

    // The displayed table is filtered+sorted; selection is keyed by
    // VISIBLE row index, not row id, so arrow keys behave intuitively
    // even after sort / filter changes (the cell at row 3 column 2
    // stays at row 3 column 2 even if the underlying row id moved).
    // This is how Excel and Google Sheets behave too.
    function cellsByRowCol(r, c) {
        const t = tableEl();
        if (!t) return null;
        const tbody = t.querySelector('tbody');
        if (!tbody) return null;
        const tr = tbody.children[r];
        if (!tr) return null;
        return tr.querySelector('[role="gridcell"][data-col-idx="' + c + '"]');
    }

    function isPrintableKey(ev) {
        // A "printable" key produces a single character of text — e.g.
        // 'a', '7', '$'. Function keys, arrows, modifiers etc. either
        // have multi-char `key` values ('ArrowDown') or are non-text.
        // ev.ctrlKey / metaKey suppress so Cmd-A et al. don't trigger
        // edit mode.
        if (ev.key.length !== 1) return false;
        if (ev.ctrlKey || ev.metaKey || ev.altKey) return false;
        return true;
    }

    function rowCount() {
        const t = tableEl();
        if (!t) return 0;
        return t.querySelectorAll('tbody > tr').length;
    }

    function colCount() {
        const cols = (app.context && app.context.columns) || [];
        return Array.isArray(cols) ? cols.length : 0;
    }

    function colAt(c) {
        const cols = (app.context && app.context.columns) || [];
        return cols[c] || null;
    }

    function rowDataAt(r) {
        // The visible row at index r. Walk the rendered tbody to find
        // its data-row-id, then look up the row in app.state.rows.
        // app.state.rows holds the SORTED+FILTERED current view (kept
        // in sync by main.js paint()).
        const t = tableEl();
        if (!t) return null;
        const tr = t.querySelectorAll('tbody > tr')[r];
        if (!tr) return null;
        const rowId = tr.getAttribute('data-row-id');
        if (rowId == null) return null;
        const all = app.state.rows || [];
        for (let i = 0; i < all.length; i++) {
            if (rowKey(all[i]) === rowId) {
                return all[i];
            }
        }
        return null;
    }

    function rowKey(row) {
        // Stable per-row identity. Each context row has a `url` (the
        // <id>.yaml.html re-edit URL); the file basename inside that
        // URL is unique per directory and survives sort/filter.
        if (!row || !row.url) return '';
        return row.url;
    }

    // --- Draft buffer -------------------------------------------------

    function getDraft(rowId, field) {
        const r = app.state.drafts[rowId];
        if (!r) return undefined;
        return r[field];
    }

    function setDraft(rowId, field, value) {
        if (!app.state.drafts[rowId]) {
            app.state.drafts[rowId] = {};
        }
        app.state.drafts[rowId][field] = value;
    }

    function clearDraftField(rowId, field) {
        const r = app.state.drafts[rowId];
        if (!r) return;
        delete r[field];
        if (Object.keys(r).length === 0) {
            delete app.state.drafts[rowId];
        }
    }

    function effectiveCellValue(row, col) {
        // Display draft value if present; otherwise the row's stored
        // value. Used by render to keep the visible cell content in
        // sync with uncommitted edits.
        const drafted = getDraft(rowKey(row), col.field);
        if (drafted !== undefined) {
            return drafted;
        }
        return app.modules.util.resolveField(row.data, col.field);
    }

    // --- Selection (roving tabindex) ----------------------------------

    function setSelected(r, c, opts) {
        opts = opts || {};
        const total = rowCount();
        const cols = colCount();
        if (total === 0 || cols === 0) {
            app.state.selected = null;
            return;
        }
        if (r < 0) r = 0;
        if (r > total - 1) r = total - 1;
        if (c < 0) c = 0;
        if (c > cols - 1) c = cols - 1;

        const t = tableEl();
        if (t) {
            const all = t.querySelectorAll('[role="gridcell"]');
            for (let i = 0; i < all.length; i++) {
                all[i].setAttribute('tabindex', '-1');
                all[i].classList.remove('zddc-table__cell--selected');
            }
        }
        const target = cellAt(r, c);
        if (target) {
            target.setAttribute('tabindex', '0');
            target.classList.add('zddc-table__cell--selected');
            if (!opts.noFocus) {
                target.focus({ preventScroll: false });
            }
        }
        app.state.selected = { row: r, col: c };
    }

    function clearSelection() {
        const t = tableEl();
        if (t) {
            const all = t.querySelectorAll('[role="gridcell"]');
            for (let i = 0; i < all.length; i++) {
                all[i].setAttribute('tabindex', '-1');
                all[i].classList.remove('zddc-table__cell--selected');
            }
        }
        app.state.selected = null;
    }

    // --- Edit mode ----------------------------------------------------

    function enterEdit(initial) {
        if (!app.state.selected) return;
        if (app.state.editing) return;
        const { row: r, col: c } = app.state.selected;
        const cell = cellAt(r, c);
        if (!cell) return;
        const row = rowDataAt(r);
        const col = colAt(c);
        if (!row || !col) return;

        const currentText = (initial != null)
            ? String(initial)
            : (effectiveCellValue(row, col) == null ? '' : String(effectiveCellValue(row, col)));

        const input = document.createElement('input');
        input.type = 'text';
        input.className = 'zddc-table__cell-input';
        input.value = currentText;
        input.setAttribute('aria-label', 'Edit ' + (col.title || col.field));

        // Replace the cell's text content with the input. We don't
        // wipe innerHTML — preserves any error-marker spans Phase 2
        // adds — but wrap the input in a way that overlays the text.
        // For now: stash the original text in dataset, swap in input.
        cell.setAttribute('data-display', cell.textContent || '');
        cell.textContent = '';
        cell.appendChild(input);
        input.focus();
        // If user pressed Enter/F2, position cursor at end. If they
        // started typing a printable char, that char already replaced
        // the value; cursor is at end naturally.
        try { input.setSelectionRange(input.value.length, input.value.length); }
        catch (_) { /* type=text supports it; defensive */ }

        app.state.editing = true;

        function commit() {
            if (!app.state.editing) return;
            const newValue = input.value;
            const oldRaw = app.modules.util.resolveField(row.data, col.field);
            const oldStr = oldRaw == null ? '' : String(oldRaw);
            if (newValue === oldStr) {
                // No change — clear any draft entry for this field
                // so we don't show a "dirty" badge for a no-op edit.
                clearDraftField(rowKey(row), col.field);
            } else {
                setDraft(rowKey(row), col.field, coerceForSchema(newValue, col));
            }
            tearDown(coerceForSchema(newValue, col));
        }

        function cancel() {
            tearDown(null);  // null = restore from data-display, no draft change
        }

        function tearDown(displayValue) {
            input.removeEventListener('keydown', onKey);
            input.removeEventListener('blur', onBlur);
            const display = (displayValue != null)
                ? renderableText(displayValue, col)
                : (cell.getAttribute('data-display') || '');
            cell.removeAttribute('data-display');
            cell.textContent = display;
            app.state.editing = false;
            cell.focus({ preventScroll: false });
        }

        function onKey(ev) {
            if (ev.key === 'Enter') {
                ev.preventDefault();
                commit();
                setSelected(r + 1, c);
            } else if (ev.key === 'Escape') {
                ev.preventDefault();
                cancel();
            } else if (ev.key === 'Tab') {
                ev.preventDefault();
                commit();
                if (ev.shiftKey) {
                    moveSelection('left-wrap');
                } else {
                    moveSelection('right-wrap');
                }
            }
            // Other keys: stay in edit mode, let the input handle them.
        }

        function onBlur(_ev) {
            // Blur (focus moved elsewhere). Commit any pending value.
            // Schedule via setTimeout(0) so a programmatic refocus by
            // tearDown→cell.focus doesn't re-fire blur during teardown.
            if (app.state.editing) {
                commit();
            }
        }

        input.addEventListener('keydown', onKey);
        input.addEventListener('blur', onBlur);
    }

    function coerceForSchema(text, col) {
        // Phase 1 stores raw strings as drafts. Phase 2 will type-coerce
        // here based on the row schema (integer→Number, boolean→bool,
        // etc.). Until then, also handle the obvious case so number
        // columns don't display "42" as a string in the table.
        if (col.format === 'number' || col.format === 'integer') {
            const n = Number(text);
            if (!Number.isNaN(n) && text.trim() !== '') return n;
        }
        return text;
    }

    function renderableText(value, col) {
        return app.modules.util.formatCell(value, col.format);
    }

    // --- Keyboard nav -------------------------------------------------

    function moveSelection(dir) {
        if (!app.state.selected) return;
        let { row: r, col: c } = app.state.selected;
        const total = rowCount();
        const cols = colCount();
        if (total === 0 || cols === 0) return;

        switch (dir) {
            case 'up':         r = Math.max(0, r - 1); break;
            case 'down':       r = Math.min(total - 1, r + 1); break;
            case 'left':       c = Math.max(0, c - 1); break;
            case 'right':      c = Math.min(cols - 1, c + 1); break;
            case 'home':       c = 0; break;
            case 'end':        c = cols - 1; break;
            case 'home-row':   r = 0; c = 0; break;
            case 'end-row':    r = total - 1; c = cols - 1; break;
            case 'left-wrap':
                if (c > 0) { c--; }
                else if (r > 0) { r--; c = cols - 1; }
                break;
            case 'right-wrap':
                if (c < cols - 1) { c++; }
                else if (r < total - 1) { r++; c = 0; }
                break;
        }
        setSelected(r, c);
    }

    function onCellKey(ev) {
        if (app.state.editing) return; // input owns its own keys
        if (!app.state.selected) return;
        const { row: r, col: c } = app.state.selected;

        switch (ev.key) {
            case 'ArrowUp':    ev.preventDefault(); moveSelection('up');    return;
            case 'ArrowDown':  ev.preventDefault(); moveSelection('down');  return;
            case 'ArrowLeft':  ev.preventDefault(); moveSelection('left');  return;
            case 'ArrowRight': ev.preventDefault(); moveSelection('right'); return;
            case 'Home':
                ev.preventDefault();
                if (ev.ctrlKey || ev.metaKey) moveSelection('home-row');
                else moveSelection('home');
                return;
            case 'End':
                ev.preventDefault();
                if (ev.ctrlKey || ev.metaKey) moveSelection('end-row');
                else moveSelection('end');
                return;
            case 'Tab':
                ev.preventDefault();
                moveSelection(ev.shiftKey ? 'left-wrap' : 'right-wrap');
                return;
            case 'Enter':
            case 'F2':
                ev.preventDefault();
                enterEdit();
                return;
            case 'Escape':
                ev.preventDefault();
                clearSelection();
                return;
        }

        if (isPrintableKey(ev)) {
            // Replace value with the typed character (Excel convention).
            ev.preventDefault();
            enterEdit(ev.key);
        }
    }

    // --- Wiring -------------------------------------------------------

    function attachToTable() {
        const t = tableEl();
        if (!t) return;
        t.setAttribute('role', 'grid');
        t.addEventListener('keydown', onCellKey);
    }

    function attachToRow(tr, rowId) {
        tr.setAttribute('role', 'row');
        tr.setAttribute('data-row-id', rowId);
    }

    function attachToCell(td, rowIdx, colIdx) {
        td.setAttribute('role', 'gridcell');
        td.setAttribute('data-col-idx', String(colIdx));
        td.setAttribute('data-row-idx', String(rowIdx));
        td.setAttribute('tabindex', '-1');

        td.addEventListener('click', function (ev) {
            ev.stopPropagation();
            setSelected(rowIdx, colIdx);
        });
        td.addEventListener('dblclick', function (ev) {
            ev.stopPropagation();
            setSelected(rowIdx, colIdx, { noFocus: true });
            enterEdit();
        });
    }

    app.modules.editor = {
        attachToTable: attachToTable,
        attachToRow: attachToRow,
        attachToCell: attachToCell,
        setSelected: setSelected,
        clearSelection: clearSelection,
        moveSelection: moveSelection,
        enterEdit: enterEdit,
        rowKey: rowKey,
        getDraft: getDraft,
        setDraft: setDraft,
        clearDraftField: clearDraftField,
        effectiveCellValue: effectiveCellValue
    };
})(window.tablesApp);