# pdf_reports.py
import os
import uuid
from datetime import datetime
from reportlab.lib.pagesizes import A4
from reportlab.lib.styles import ParagraphStyle, getSampleStyleSheet
from reportlab.lib.enums import TA_CENTER, TA_RIGHT, TA_JUSTIFY, TA_LEFT
from reportlab.lib import colors
from reportlab.platypus import (
    BaseDocTemplate, PageTemplate, Frame, Paragraph, Spacer, Table, TableStyle
)
from reportlab.pdfbase.ttfonts import TTFont
from reportlab.pdfbase import pdfmetrics

# Try to load a nicer serif; fallback to Times
try:
    pdfmetrics.registerFont(TTFont('DejaVuSerif', '/usr/share/fonts/truetype/dejavu/DejaVuSerif.ttf'))
    BODY_FONT = 'DejaVuSerif'
except Exception:
    BODY_FONT = 'Times-Roman'


def _build_doc(filepath, title_text, tiles, counts, sections, matched_sources, footer_text):
    PAGE_WIDTH, PAGE_HEIGHT = A4
    MARGIN = 36
    usable_width = PAGE_WIDTH - 2 * MARGIN

    styles = getSampleStyleSheet()
    styles.add(ParagraphStyle(name='ReportTitle', fontName=BODY_FONT, fontSize=18, alignment=TA_CENTER, leading=22))
    styles.add(ParagraphStyle(name='SmallRight', fontName=BODY_FONT, fontSize=9, alignment=TA_RIGHT, textColor=colors.HexColor("#555555")))
    styles.add(ParagraphStyle(name='TileBig', fontName=BODY_FONT, fontSize=30, alignment=TA_CENTER, leading=32))
    styles.add(ParagraphStyle(name='TileLabel', fontName=BODY_FONT, fontSize=10, alignment=TA_CENTER, textColor=colors.HexColor("#666666")))
    styles.add(ParagraphStyle(name='SectionHeading', fontName=BODY_FONT, fontSize=13, spaceBefore=8, spaceAfter=4, leading=15))
    styles.add(ParagraphStyle(name='Body', fontName=BODY_FONT, fontSize=11, leading=15, alignment=TA_JUSTIFY))
    styles.add(ParagraphStyle(name='HighlightYellow', fontName=BODY_FONT, fontSize=11, leading=15, backColor=colors.HexColor("#fff3b0"), alignment=TA_JUSTIFY))
    styles.add(ParagraphStyle(name='HighlightRed', fontName=BODY_FONT, fontSize=11, leading=15, backColor=colors.HexColor("#ffd6d6"), alignment=TA_JUSTIFY))
    styles.add(ParagraphStyle(name='Footer', fontName=BODY_FONT, fontSize=9, alignment=TA_RIGHT, textColor=colors.HexColor("#666666")))
    styles.add(ParagraphStyle(name='MatchedHeader', fontName=BODY_FONT, fontSize=12, leading=14, alignment=TA_LEFT, spaceBefore=6, spaceAfter=6))

    def header_footer(canvas, doc):
        canvas.saveState()
        date_str = datetime.now().strftime("%d %B %Y, %H:%M")
        canvas.setFont(BODY_FONT, 9)
        canvas.setFillColor(colors.HexColor("#555555"))
        canvas.drawString(MARGIN, PAGE_HEIGHT - MARGIN + 8, f"Date: {date_str}")
        canvas.setFont(BODY_FONT, 16)
        canvas.setFillColor(colors.black)
        canvas.drawCentredString(PAGE_WIDTH / 2.0, PAGE_HEIGHT - MARGIN + 4, title_text)
        canvas.setFont(BODY_FONT, 9)
        canvas.setFillColor(colors.HexColor("#666666"))
        canvas.drawRightString(PAGE_WIDTH - MARGIN, MARGIN - 10, f"Page {doc.page}")
        canvas.restoreState()

    doc = BaseDocTemplate(filepath, pagesize=A4,
                          leftMargin=MARGIN, rightMargin=MARGIN,
                          topMargin=MARGIN, bottomMargin=MARGIN)
    frame = Frame(MARGIN, MARGIN, usable_width, PAGE_HEIGHT - 2 * MARGIN, id='normal')
    template = PageTemplate(id='report', frames=[frame], onPage=header_footer)
    doc.addPageTemplates([template])

    story = []

    # Tiles (4 small summary tiles)
    tile_values = tiles  # list of 4 dicts: {'value': '12%', 'label': 'Plagiarism'}
    tiles_data = [
        [Paragraph(f"<b>{tile_values[i]['value']}</b>", styles['TileBig']) for i in range(4)],
        [Paragraph(tile_values[i]['label'], styles['TileLabel']) for i in range(4)]
    ]
    tiles_table = Table(tiles_data, colWidths=[usable_width / 4.0] * 4, rowHeights=[46, 18])
    tiles_table.setStyle(TableStyle([
        ('BACKGROUND', (0, 0), (-1, 0), colors.HexColor("#f7f7f9")),
        ('ALIGN', (0, 0), (-1, -1), 'CENTER'),
        ('VALIGN', (0, 0), (-1, -1), 'MIDDLE'),
        ('BOX', (0, 0), (-1, -1), 0.6, colors.HexColor("#dddddd")),
    ]))
    story.append(tiles_table)
    story.append(Spacer(1, 12))

    # Counts row
    if counts:
        counts_table = Table([list(counts.keys()), list(counts.values())],
                             colWidths=[usable_width / len(counts)] * len(counts))
        counts_table.setStyle(TableStyle([
            ('BACKGROUND', (0, 0), (-1, 0), colors.HexColor("#f4f6f7")),
            ('ALIGN', (0, 0), (-1, -1), 'CENTER'),
            ('BOX', (0, 0), (-1, -1), 0.5, colors.HexColor("#e6e6e6")),
        ]))
        story.append(counts_table)
        story.append(Spacer(1, 12))

    # Sections + highlighting: sections is list of dicts: {'heading': 'Abstract', 'paragraphs': [p1, p2...]}
    for sec in sections or []:
        if sec.get('heading'):
            story.append(Paragraph(sec['heading'], styles['SectionHeading']))
        for para in sec.get('paragraphs', []):
            # para may be dict {'text': '...', 'highlight':'yellow'/'red'/None}
            if isinstance(para, dict):
                text = para.get('text', '')
                hl = para.get('highlight')
                if hl == 'yellow':
                    story.append(Paragraph(text, styles['HighlightYellow']))
                elif hl == 'red':
                    story.append(Paragraph(text, styles['HighlightRed']))
                else:
                    story.append(Paragraph(text, styles['Body']))
            else:
                story.append(Paragraph(para, styles['Body']))
            story.append(Spacer(1, 6))

    story.append(Spacer(1, 10))

    # Matched Sources table (if any)
    if matched_sources:
        story.append(Paragraph("Matched Sources", styles['MatchedHeader']))
        ms_table_data = [["#", "Source Title", "URL", "Similarity"]]
        for i, ms in enumerate(matched_sources, start=1):
            title_par = Paragraph(ms.get('title', ''), styles['Body'])
            url_par = Paragraph(f'<link href="{ms.get("url", "")}">{ms.get("url", "")}</link>', styles['Body'])
            ms_table_data.append([str(i), title_par, url_par, ms.get('similarity', '')])
        ms_table = Table(ms_table_data, colWidths=[30, usable_width * 0.35, usable_width * 0.45, usable_width * 0.15])
        ms_table.setStyle(TableStyle([
            ('BACKGROUND', (0, 0), (-1, 0), colors.HexColor("#f2f4f5")),
            ('TEXTCOLOR', (0, 0), (-1, 0), colors.HexColor("#333333")),
            ('ALIGN', (0, 0), (-1, 0), 'CENTER'),
            ('VALIGN', (0, 0), (-1, -1), 'MIDDLE'),
            ('BOX', (0, 0), (-1, -1), 0.6, colors.HexColor("#e0e0e0")),
            ('INNERGRID', (0, 0), (-1, -1), 0.4, colors.HexColor("#efefef")),
            ('LEFTPADDING', (1, 1), (1, -1), 6),
            ('LEFTPADDING', (2, 1), (2, -1), 6),
        ]))
        story.append(ms_table)
        story.append(Spacer(1, 14))

    # Matched Source Overview block (footer_text)
    if footer_text:
        matched_table = Table(
            [[Paragraph("<b>Matched Source Overview</b>", styles['Body'])],
             [Paragraph(footer_text, styles['Body'])]],
            colWidths=[usable_width]
        )
        matched_table.setStyle(TableStyle([
            ('BACKGROUND', (0, 0), (-1, 0), colors.HexColor("#f7fafb")),
            ('BOX', (0, 0), (-1, -1), 0.5, colors.HexColor("#e6e6e6")),
            ('LEFTPADDING', (0, 0), (-1, -1), 8),
            ('RIGHTPADDING', (0, 0), (-1, -1), 8),
            ('TOPPADDING', (0, 0), (-1, -1), 6),
            ('BOTTOMPADDING', (0, 0), (-1, -1), 6),
        ]))
        story.append(matched_table)
        story.append(Spacer(1, 24))

    story.append(Paragraph("Generated by TrueWrite Scan • https://gopalkrushnamahapatra-truewrite-scan.static.hf.space", styles['Footer']))

    doc.build(story)


def generate_report(report_type: str, out_dir: str = "/tmp", **kwargs) -> str:
    """
    report_type: "ai" | "grammar" | "plagiarism"
    kwargs expected:
      - title_text: str
      - tiles: list of 4 dicts [{'value': '12%', 'label': 'Plagiarism'}, ...]
      - counts: dict {'Words': 950, ...}
      - sections: list [{'heading':'','paragraphs':[...]}]
      - matched_sources: list [{'title','url','similarity'}]
      - footer_text: str
    Returns: path to generated PDF
    """
    os.makedirs(out_dir, exist_ok=True)
    filename = f"{report_type}_report_{uuid.uuid4().hex[:8]}.pdf"
    filepath = os.path.join(out_dir, filename)

    title_text = kwargs.get('title_text', "Report")
    tiles = kwargs.get('tiles') or [
        {'value': '0%', 'label': 'Plagiarism'},
        {'value': '0%', 'label': 'Exact Match'},
        {'value': '0%', 'label': 'Partial Match'},
        {'value': '100%', 'label': 'Unique'},
    ]
    counts = kwargs.get('counts') or {}
    sections = kwargs.get('sections') or []
    matched_sources = kwargs.get('matched_sources') or []
    footer_text = kwargs.get('footer_text') or ''

    _build_doc(filepath, title_text, tiles, counts, sections, matched_sources, footer_text)
    return filepath