fix: PDF generator - always one page, canvas API, improved layout

app/core/pdf_generator.py

@@ -1,289 +1,317 @@
 """
-PDF generation for Scenar Creator v3 using ReportLab.
-Generates A4 landscape timetable PDF with colored blocks and legend.
+PDF generation for Scenar Creator v3 using ReportLab Canvas API.
+Generates A4 landscape timetable — always exactly one page.
 """
 
 from io import BytesIO
 from datetime import datetime
 from collections import defaultdict
-from reportlab.lib import colors
 from reportlab.lib.pagesizes import A4, landscape
 from reportlab.lib.units import mm
-from reportlab.platypus import SimpleDocTemplate, Table, TableStyle, Paragraph, Spacer
-from reportlab.lib.styles import getSampleStyleSheet, ParagraphStyle
-from reportlab.lib.enums import TA_CENTER, TA_LEFT, TA_RIGHT
+from reportlab.pdfgen import canvas as rl_canvas
 import logging
 
 from .validator import ScenarsError
 
 logger = logging.getLogger(__name__)
 
+PAGE_W, PAGE_H = landscape(A4)
+MARGIN = 10 * mm
 
-def hex_to_reportlab_color(hex_color: str) -> colors.Color:
-    """Convert #RRGGBB hex color to ReportLab color."""
+# Color palette for UI
+HEADER_BG = (0.118, 0.161, 0.231)   # dark navy
+GRID_LINE = (0.85, 0.85, 0.85)
+HEADER_TEXT = (1.0, 1.0, 1.0)
+BODY_ALT = (0.97, 0.97, 0.97)
+FOOTER_TEXT = (0.6, 0.6, 0.6)
+LABEL_TEXT = (0.35, 0.35, 0.35)
+
+
+def hex_to_rgb(hex_color: str) -> tuple:
     h = hex_color.lstrip('#')
     if len(h) == 8:
         h = h[2:]
-    if len(h) == 6:
-        r, g, b = int(h[0:2], 16), int(h[2:4], 16), int(h[4:6], 16)
-        return colors.Color(r / 255.0, g / 255.0, b / 255.0)
-    return colors.white
+    if len(h) != 6:
+        return (0.8, 0.8, 0.8)
+    r = int(h[0:2], 16) / 255.0
+    g = int(h[2:4], 16) / 255.0
+    b = int(h[4:6], 16) / 255.0
+    return (r, g, b)
 
 
-def is_light_color(hex_color: str) -> bool:
-    """Check if a color is light (needs dark text)."""
-    h = hex_color.lstrip('#')
-    if len(h) == 8:
-        h = h[2:]
-    if len(h) == 6:
-        r, g, b = int(h[0:2], 16), int(h[2:4], 16), int(h[4:6], 16)
-        luminance = (0.299 * r + 0.587 * g + 0.114 * b) / 255
-        return luminance > 0.6
-    return False
+def is_light(hex_color: str) -> bool:
+    r, g, b = hex_to_rgb(hex_color)
+    return (0.299 * r + 0.587 * g + 0.114 * b) > 0.6
 
 
-def time_to_minutes(time_str: str) -> int:
-    """Convert HH:MM to minutes since midnight."""
-    parts = time_str.split(":")
-    return int(parts[0]) * 60 + int(parts[1])
+def time_to_minutes(s: str) -> int:
+    h, m = s.split(":")
+    return int(h) * 60 + int(m)
+
+
+def fmt_time(total_minutes: int) -> str:
+    return f"{total_minutes // 60:02d}:{total_minutes % 60:02d}"
+
+
+def set_fill(c, rgb):
+    c.setFillColorRGB(*rgb)
+
+
+def set_stroke(c, rgb):
+    c.setStrokeColorRGB(*rgb)
+
+
+def draw_rect_filled(c, x, y, w, h, fill_rgb, stroke_rgb=None, stroke_width=0.5):
+    set_fill(c, fill_rgb)
+    if stroke_rgb:
+        set_stroke(c, stroke_rgb)
+        c.setLineWidth(stroke_width)
+        c.rect(x, y, w, h, fill=1, stroke=1)
+    else:
+        c.rect(x, y, w, h, fill=1, stroke=0)
+
+
+def draw_text_clipped(c, text, x, y, w, h, font, size, rgb, align="center"):
+    """Draw text centered/left in a bounding box, clipped to width."""
+    c.saveState()
+    c.rect(x, y, w, h, fill=0, stroke=0)
+    c.clipPath(c.beginPath(), stroke=0, fill=0)
+    # Use a proper clip path
+    p = c.beginPath()
+    p.rect(x, y, w, h)
+    c.clipPath(p, stroke=0, fill=0)
+    set_fill(c, rgb)
+    c.setFont(font, size)
+    if align == "center":
+        c.drawCentredString(x + w / 2, y + (h - size) / 2 + 1, text)
+    elif align == "right":
+        c.drawRightString(x + w - 2, y + (h - size) / 2 + 1, text)
+    else:
+        c.drawString(x + 2, y + (h - size) / 2 + 1, text)
+    c.restoreState()
 
 
 def generate_pdf(doc) -> bytes:
-    """
-    Generate a PDF timetable from a ScenarioDocument.
-
-    Args:
-        doc: ScenarioDocument instance
-
-    Returns:
-        bytes: PDF file content
-    """
     if not doc.blocks:
         raise ScenarsError("No blocks provided")
 
     type_map = {pt.id: pt for pt in doc.program_types}
     for block in doc.blocks:
         if block.type_id not in type_map:
-            raise ScenarsError(
-                f"Missing type definition: '{block.type_id}'. "
-                "Please define all program types."
-            )
+            raise ScenarsError(f"Missing type definition: '{block.type_id}'")
 
-    buffer = BytesIO()
-    page_w, page_h = landscape(A4)
-    doc_pdf = SimpleDocTemplate(
-        buffer,
-        pagesize=landscape(A4),
-        leftMargin=12 * mm,
-        rightMargin=12 * mm,
-        topMargin=12 * mm,
-        bottomMargin=12 * mm,
-    )
-
-    styles = getSampleStyleSheet()
-    title_style = ParagraphStyle(
-        'TimetableTitle', parent=styles['Title'],
-        fontSize=20, alignment=TA_LEFT, spaceAfter=1 * mm,
-        textColor=colors.Color(0.118, 0.161, 0.231),
-        fontName='Helvetica-Bold'
-    )
-    subtitle_style = ParagraphStyle(
-        'TimetableSubtitle', parent=styles['Normal'],
-        fontSize=12, alignment=TA_LEFT, spaceAfter=1 * mm,
-        textColor=colors.Color(0.4, 0.4, 0.4),
-        fontName='Helvetica'
-    )
-    info_style = ParagraphStyle(
-        'InfoStyle', parent=styles['Normal'],
-        fontSize=10, alignment=TA_LEFT, spaceAfter=4 * mm,
-        textColor=colors.Color(0.5, 0.5, 0.5),
-        fontName='Helvetica'
-    )
-    cell_style_white = ParagraphStyle(
-        'CellStyleWhite', parent=styles['Normal'],
-        fontSize=8, alignment=TA_CENTER, leading=10,
-        textColor=colors.white, fontName='Helvetica-Bold'
-    )
-    cell_style_dark = ParagraphStyle(
-        'CellStyleDark', parent=styles['Normal'],
-        fontSize=8, alignment=TA_CENTER, leading=10,
-        textColor=colors.Color(0.1, 0.1, 0.1), fontName='Helvetica-Bold'
-    )
-    time_style = ParagraphStyle(
-        'TimeStyle', parent=styles['Normal'],
-        fontSize=7, alignment=TA_RIGHT, leading=9,
-        textColor=colors.Color(0.5, 0.5, 0.5), fontName='Helvetica'
-    )
-    legend_style = ParagraphStyle(
-        'LegendStyle', parent=styles['Normal'],
-        fontSize=9, alignment=TA_LEFT, fontName='Helvetica'
-    )
-    footer_style = ParagraphStyle(
-        'FooterStyle', parent=styles['Normal'],
-        fontSize=8, alignment=TA_CENTER,
-        textColor=colors.Color(0.6, 0.6, 0.6), fontName='Helvetica-Oblique'
-    )
-
-    elements = []
-
-    # Header
-    elements.append(Paragraph(doc.event.title, title_style))
-    if doc.event.subtitle:
-        elements.append(Paragraph(doc.event.subtitle, subtitle_style))
-
-    info_parts = []
-    if doc.event.date:
-        info_parts.append(f"Datum: {doc.event.date}")
-    if doc.event.location:
-        info_parts.append(f"M\u00edsto: {doc.event.location}")
-    if info_parts:
-        elements.append(Paragraph(" | ".join(info_parts), info_style))
-
-    elements.append(Spacer(1, 3 * mm))
-
-    # Group blocks by date
+    # Group by date
     blocks_by_date = defaultdict(list)
-    for block in doc.blocks:
-        blocks_by_date[block.date].append(block)
-
+    for b in doc.blocks:
+        blocks_by_date[b.date].append(b)
     sorted_dates = sorted(blocks_by_date.keys())
 
-    # Find global time range
+    # Time range (round to 30-min boundaries)
     all_starts = [time_to_minutes(b.start) for b in doc.blocks]
     all_ends = [time_to_minutes(b.end) for b in doc.blocks]
-    global_start = (min(all_starts) // 30) * 30
-    global_end = ((max(all_ends) + 29) // 30) * 30
+    t_start = (min(all_starts) // 30) * 30
+    t_end = ((max(all_ends) + 29) // 30) * 30
+    slot_minutes = 30
+    num_slots = (t_end - t_start) // slot_minutes
 
-    # Generate 30-min time slots
-    time_slots = []
-    t = global_start
-    while t <= global_end:
-        h, m = divmod(t, 60)
-        time_slots.append(f"{h:02d}:{m:02d}")
-        t += 30
+    buf = BytesIO()
+    c = rl_canvas.Canvas(buf, pagesize=landscape(A4))
 
-    # Build table: time column + one column per day
-    header = [""] + [d for d in sorted_dates]
+    # ── Layout constants ──────────────────────────────────────────────
+    x0 = MARGIN
+    y_top = PAGE_H - MARGIN
 
-    table_data = [header]
-    slot_count = len(time_slots) - 1
+    # Header block
+    title_size = 16
+    subtitle_size = 10
+    info_size = 8
+    header_h = title_size + 4
 
-    # Build grid and track colored cells
-    cell_colors_list = []
+    has_subtitle = bool(doc.event.subtitle)
+    has_info = bool(doc.event.date or doc.event.location)
+    if has_subtitle:
+        header_h += subtitle_size + 2
+    if has_info:
+        header_h += info_size + 2
+    header_h += 4  # bottom padding
 
-    for slot_idx in range(slot_count):
-        slot_start = time_slots[slot_idx]
-        slot_end = time_slots[slot_idx + 1]
-        row = [Paragraph(slot_start, time_style)]
-
-        for date_key in sorted_dates:
-            cell_content = ""
-            for block in blocks_by_date[date_key]:
-                block_start_min = time_to_minutes(block.start)
-                block_end_min = time_to_minutes(block.end)
-                slot_start_min = time_to_minutes(slot_start)
-                slot_end_min = time_to_minutes(slot_end)
-
-                if block_start_min <= slot_start_min and block_end_min >= slot_end_min:
-                    pt = type_map[block.type_id]
-                    light = is_light_color(pt.color)
-                    cs = cell_style_dark if light else cell_style_white
-
-                    if block_start_min == slot_start_min:
-                        label = block.title
-                        if block.responsible:
-                            label += f"<br/><font size='6'>{block.responsible}</font>"
-                        cell_content = Paragraph(label, cs)
-                    else:
-                        cell_content = ""
-                    cell_colors_list.append((len(table_data), len(row), pt.color))
-                    break
-
-            row.append(cell_content if cell_content else "")
-
-        table_data.append(row)
-
-    # Column widths
-    avail_width = page_w - 24 * mm
-    time_col_width = 18 * mm
-    day_col_width = (avail_width - time_col_width) / max(len(sorted_dates), 1)
-    col_widths = [time_col_width] + [day_col_width] * len(sorted_dates)
-
-    row_height = 20
-    table = Table(table_data, colWidths=col_widths, rowHeights=[24] + [row_height] * slot_count)
-
-    style_cmds = [
-        ('BACKGROUND', (0, 0), (-1, 0), colors.Color(0.118, 0.161, 0.231)),
-        ('TEXTCOLOR', (0, 0), (-1, 0), colors.white),
-        ('FONTNAME', (0, 0), (-1, 0), 'Helvetica-Bold'),
-        ('FONTSIZE', (0, 0), (-1, 0), 10),
-        ('ALIGN', (0, 0), (-1, 0), 'CENTER'),
-        ('VALIGN', (0, 0), (-1, -1), 'MIDDLE'),
-        ('ALIGN', (0, 1), (0, -1), 'RIGHT'),
-        ('FONTSIZE', (0, 1), (-1, -1), 7),
-        ('GRID', (0, 0), (-1, -1), 0.5, colors.Color(0.85, 0.85, 0.85)),
-        ('LINEBELOW', (0, 0), (-1, 0), 1.5, colors.Color(0.118, 0.161, 0.231)),
-        ('ROWBACKGROUNDS', (1, 1), (-1, -1), [colors.white, colors.Color(0.98, 0.98, 0.98)]),
-    ]
-
-    for r, c, hex_clr in cell_colors_list:
-        rl_color = hex_to_reportlab_color(hex_clr)
-        style_cmds.append(('BACKGROUND', (c, r), (c, r), rl_color))
-
-    # Merge cells for blocks spanning multiple time slots
-    for date_idx, date_key in enumerate(sorted_dates):
-        col = date_idx + 1
-        for block in blocks_by_date[date_key]:
-            block_start_min = time_to_minutes(block.start)
-            block_end_min = time_to_minutes(block.end)
-
-            start_row = None
-            end_row = None
-            for slot_idx in range(slot_count):
-                slot_min = time_to_minutes(time_slots[slot_idx])
-                if slot_min == block_start_min:
-                    start_row = slot_idx + 1
-                if slot_idx + 1 < len(time_slots):
-                    next_slot_min = time_to_minutes(time_slots[slot_idx + 1])
-                    if next_slot_min == block_end_min:
-                        end_row = slot_idx + 1
-
-            if start_row is not None and end_row is not None and end_row > start_row:
-                style_cmds.append(('SPAN', (col, start_row), (col, end_row)))
-
-    table.setStyle(TableStyle(style_cmds))
-    elements.append(table)
-
-    # Legend
-    elements.append(Spacer(1, 5 * mm))
-    legend_items = []
-    for pt in doc.program_types:
-        legend_items.append([Paragraph(f"  {pt.name}", legend_style)])
-
-    if legend_items:
-        elements.append(Paragraph("<b>Legenda:</b>", legend_style))
-        elements.append(Spacer(1, 2 * mm))
-        legend_table = Table(legend_items, colWidths=[60 * mm])
-        legend_cmds = [
-            ('VALIGN', (0, 0), (-1, -1), 'MIDDLE'),
-            ('BOX', (0, 0), (-1, -1), 0.5, colors.Color(0.85, 0.85, 0.85)),
-            ('INNERGRID', (0, 0), (-1, -1), 0.5, colors.Color(0.85, 0.85, 0.85)),
-        ]
-        for i, pt in enumerate(doc.program_types):
-            rl_color = hex_to_reportlab_color(pt.color)
-            legend_cmds.append(('BACKGROUND', (0, i), (0, i), rl_color))
-            if not is_light_color(pt.color):
-                legend_cmds.append(('TEXTCOLOR', (0, i), (0, i), colors.white))
-        legend_table.setStyle(TableStyle(legend_cmds))
-        elements.append(legend_table)
+    # Legend block (one row per type)
+    legend_item_h = 12
+    legend_h = len(doc.program_types) * legend_item_h + 6
 
     # Footer
-    elements.append(Spacer(1, 5 * mm))
-    gen_date = datetime.now().strftime("%d.%m.%Y %H:%M")
-    elements.append(Paragraph(
-        f"Vygenerov\u00e1no Scen\u00e1r Creatorem | {gen_date}",
-        footer_style
-    ))
+    footer_h = 10
 
-    doc_pdf.build(elements)
-    return buffer.getvalue()
+    # Available height for timetable
+    avail_h = PAGE_H - 2 * MARGIN - header_h - legend_h - footer_h - 6
+    row_h = max(8, avail_h / max(num_slots, 1))
+
+    # Time axis width
+    time_col_w = 14 * mm
+    # Column widths for dates
+    avail_w = PAGE_W - 2 * MARGIN - time_col_w
+    day_col_w = avail_w / max(len(sorted_dates), 1)
+
+    # Font sizes scale with row height
+    cell_font_size = max(5.5, min(8.0, row_h * 0.45))
+    time_font_size = max(5.0, min(7.0, row_h * 0.42))
+    header_col_size = max(6.0, min(9.0, day_col_w * 0.08))
+
+    # ── Draw header ───────────────────────────────────────────────────
+    y = y_top
+    c.setFont("Helvetica-Bold", title_size)
+    set_fill(c, HEADER_BG)
+    c.drawString(x0, y - title_size, doc.event.title)
+    y -= title_size + 4
+
+    if has_subtitle:
+        c.setFont("Helvetica", subtitle_size)
+        set_fill(c, (0.4, 0.4, 0.4))
+        c.drawString(x0, y - subtitle_size, doc.event.subtitle)
+        y -= subtitle_size + 2
+
+    if has_info:
+        parts = []
+        if doc.event.date:
+            parts.append(f"Datum: {doc.event.date}")
+        if doc.event.location:
+            parts.append(f"Místo: {doc.event.location}")
+        c.setFont("Helvetica", info_size)
+        set_fill(c, (0.5, 0.5, 0.5))
+        c.drawString(x0, y - info_size, " | ".join(parts))
+        y -= info_size + 2
+
+    y -= 6  # padding before table
+
+    # ── Draw column headers ───────────────────────────────────────────
+    col_header_h = 16
+    # Time axis header cell
+    draw_rect_filled(c, x0, y - col_header_h, time_col_w, col_header_h, HEADER_BG)
+    # Date header cells
+    for di, date_key in enumerate(sorted_dates):
+        cx = x0 + time_col_w + di * day_col_w
+        draw_rect_filled(c, cx, y - col_header_h, day_col_w, col_header_h, HEADER_BG, GRID_LINE)
+        c.saveState()
+        p = c.beginPath()
+        p.rect(cx + 1, y - col_header_h + 1, day_col_w - 2, col_header_h - 2)
+        c.clipPath(p, stroke=0, fill=0)
+        set_fill(c, HEADER_TEXT)
+        c.setFont("Helvetica-Bold", header_col_size)
+        c.drawCentredString(cx + day_col_w / 2, y - col_header_h + (col_header_h - header_col_size) / 2, date_key)
+        c.restoreState()
+
+    y -= col_header_h
+
+    # ── Draw time grid ────────────────────────────────────────────────
+    table_top = y
+    table_bottom = y - num_slots * row_h
+
+    for slot_i in range(num_slots):
+        slot_min = t_start + slot_i * slot_minutes
+        slot_label = fmt_time(slot_min)
+        row_y = y - slot_i * row_h
+
+        # Alternating row bg for day columns
+        alt_bg = BODY_ALT if slot_i % 2 == 1 else (1.0, 1.0, 1.0)
+        for di in range(len(sorted_dates)):
+            cx = x0 + time_col_w + di * day_col_w
+            draw_rect_filled(c, cx, row_y - row_h, day_col_w, row_h, alt_bg, GRID_LINE, 0.3)
+
+        # Time axis cell
+        draw_rect_filled(c, x0, row_y - row_h, time_col_w, row_h, (0.96, 0.96, 0.96), GRID_LINE, 0.3)
+        set_fill(c, LABEL_TEXT)
+        c.setFont("Helvetica", time_font_size)
+        c.drawRightString(x0 + time_col_w - 2, row_y - row_h + (row_h - time_font_size) / 2, slot_label)
+
+    # ── Draw program blocks ───────────────────────────────────────────
+    for di, date_key in enumerate(sorted_dates):
+        cx = x0 + time_col_w + di * day_col_w
+        for block in blocks_by_date[date_key]:
+            b_start = time_to_minutes(block.start)
+            b_end = time_to_minutes(block.end)
+            if b_start < t_start or b_end > t_end:
+                continue
+            offset_slots_start = (b_start - t_start) / slot_minutes
+            offset_slots_end = (b_end - t_start) / slot_minutes
+            block_top = table_top - offset_slots_start * row_h
+            block_bot = table_top - offset_slots_end * row_h
+            block_h = block_top - block_bot
+
+            pt = type_map[block.type_id]
+            fill_rgb = hex_to_rgb(pt.color)
+            text_rgb = (0.1, 0.1, 0.1) if is_light(pt.color) else (1.0, 1.0, 1.0)
+
+            # Block rectangle with slight inset
+            inset = 0.5
+            bx = cx + inset
+            by = block_bot + inset
+            bw = day_col_w - 2 * inset
+            bh = block_h - 2 * inset
+
+            c.saveState()
+            draw_rect_filled(c, bx, by, bw, bh, fill_rgb, GRID_LINE, 0.5)
+
+            # Clip text to block
+            p = c.beginPath()
+            p.rect(bx + 1, by + 1, bw - 2, bh - 2)
+            c.clipPath(p, stroke=0, fill=0)
+
+            set_fill(c, text_rgb)
+            lines = [block.title]
+            if block.responsible:
+                lines.append(block.responsible)
+
+            if len(lines) == 1 or bh < cell_font_size * 2.5:
+                c.setFont("Helvetica-Bold", cell_font_size)
+                c.drawCentredString(bx + bw / 2, by + (bh - cell_font_size) / 2, lines[0])
+            else:
+                c.setFont("Helvetica-Bold", cell_font_size)
+                c.drawCentredString(bx + bw / 2, by + bh / 2 + 1, lines[0])
+                c.setFont("Helvetica", max(4.5, cell_font_size - 1.0))
+                set_fill(c, (text_rgb[0] * 0.85, text_rgb[1] * 0.85, text_rgb[2] * 0.85) if is_light(pt.color)
+                         else (0.9, 0.9, 0.9))
+                c.drawCentredString(bx + bw / 2, by + bh / 2 - cell_font_size + 1, lines[1])
+
+            c.restoreState()
+
+    # ── Legend ────────────────────────────────────────────────────────
+    legend_y = table_bottom - 8
+    legend_x = x0
+    legend_label_h = legend_item_h
+
+    c.setFont("Helvetica-Bold", 7)
+    set_fill(c, HEADER_BG)
+    c.drawString(legend_x, legend_y, "Legenda:")
+    legend_y -= 4
+
+    legend_box_w = 10 * mm
+    legend_text_w = 50 * mm
+    legend_col_stride = legend_box_w + legend_text_w + 4 * mm
+    cols = max(1, int((PAGE_W - 2 * MARGIN) / legend_col_stride))
+
+    for i, pt in enumerate(doc.program_types):
+        col = i % cols
+        row_idx = i // cols
+        lx = legend_x + col * legend_col_stride
+        ly = legend_y - row_idx * legend_label_h
+
+        fill_rgb = hex_to_rgb(pt.color)
+        text_rgb = (0.1, 0.1, 0.1) if is_light(pt.color) else (1.0, 1.0, 1.0)
+
+        draw_rect_filled(c, lx, ly - legend_label_h + 2, legend_box_w, legend_label_h - 2, fill_rgb, GRID_LINE, 0.3)
+        c.setFont("Helvetica-Bold", 6.5)
+        set_fill(c, text_rgb)
+        c.drawCentredString(lx + legend_box_w / 2, ly - legend_label_h + 2 + (legend_label_h - 2 - 6.5) / 2, pt.name[:10])
+
+        c.setFont("Helvetica", 7)
+        set_fill(c, LABEL_TEXT)
+        c.drawString(lx + legend_box_w + 2, ly - legend_label_h + 2 + (legend_label_h - 2 - 7) / 2, pt.name)
+
+    # ── Footer ────────────────────────────────────────────────────────
+    gen_date = datetime.now().strftime("%d.%m.%Y %H:%M")
+    c.setFont("Helvetica-Oblique", 6.5)
+    set_fill(c, FOOTER_TEXT)
+    c.drawCentredString(PAGE_W / 2, MARGIN - 2, f"Vygenerováno Scenár Creatorem | {gen_date}")
+
+    c.save()
+    return buf.getvalue()