"""
Nightly Report Renderers.

Pluggable renderers over the `report_pipeline` data model.  v1 ships the HTML
email body + the Excel attachment; PDF and an inline chart image are v1.1
(each needs a new dependency).  Keeping renderers separate from the compute
core means a future report wizard just toggles metrics/renderers — the data
model is unchanged.

Email-client constraints: the HTML uses a table layout with **inline styles
only** (no <style> blocks, no external CSS, no fl/grid), which is the reliable
common denominator across Outlook / Gmail / Apple Mail.
"""

from __future__ import annotations

from html import escape

from backend.services.report_pipeline import ProjectNightReport, LocationNightReport


# Colours: louder-than-baseline reads as a concern (red), quieter as fine (green).
_RED = "#b00020"
_GREEN = "#1a7f37"
_GREY = "#888888"


def _fmt_value(v) -> str:
    return f"{v:.1f}" if isinstance(v, (int, float)) else "—"


def _fmt_delta(v) -> str:
    """Signed delta with colour; positive (louder) = red, negative (quieter) = green."""
    if not isinstance(v, (int, float)):
        return f'<span style="color:{_GREY}">—</span>'
    if v > 0:
        return f'<span style="color:{_RED}">+{v:.1f}</span>'
    if v < 0:
        return f'<span style="color:{_GREEN}">{v:.1f}</span>'
    return f'<span style="color:{_GREY}">0.0</span>'


def _location_table(loc: LocationNightReport) -> str:
    """One location block: heading + Metric × (window: Last / Base / Δ) table."""
    th = ('padding:5px 9px;border:1px solid #ccc;background:#f2f2f2;'
          'font:bold 12px Arial,sans-serif;text-align:center')
    sub = ('padding:4px 8px;border:1px solid #ccc;background:#fafafa;'
           'font:11px Arial,sans-serif;text-align:center;color:#555')
    td = 'padding:4px 9px;border:1px solid #ccc;font:12px Arial,sans-serif;text-align:center'
    td_l = 'padding:4px 9px;border:1px solid #ccc;font:bold 12px Arial,sans-serif;text-align:left'

    # Top header: blank label cell + each window spanning Last/Base/Δ
    top = f'<th rowspan="2" style="{th}">Metric (dBA)</th>'
    for w in loc.windows:
        top += f'<th colspan="3" style="{th}">{escape(w.label)}</th>'
    sub_row = ''.join(
        f'<th style="{sub}">Last</th><th style="{sub}">Base</th><th style="{sub}">&Delta;</th>'
        for _ in loc.windows
    )

    body = ''
    for m in loc.metrics:
        cells = ''
        for w in loc.windows:
            cp = loc.table[w.key][m.key]
            cells += (f'<td style="{td}">{_fmt_value(cp.last_night)}</td>'
                      f'<td style="{td}">{_fmt_value(cp.baseline)}</td>'
                      f'<td style="{td}">{_fmt_delta(cp.delta)}</td>')
        body += f'<tr><td style="{td_l}">{escape(m.label)}</td>{cells}</tr>'

    meta = (f'{loc.night_interval_count} intervals'
            + (f' · baseline = {loc.baseline_nights_used} night(s)'
               if loc.baseline_nights_used else ' · no baseline yet'))
    notes = ''
    if loc.notes:
        notes = ('<div style="font:11px Arial,sans-serif;color:#b00020;margin:2px 0 0">'
                 + '<br>'.join(escape(n) for n in loc.notes) + '</div>')

    return (
        f'<h3 style="font:bold 15px Arial,sans-serif;margin:18px 0 4px">{escape(loc.location_name)}</h3>'
        f'<div style="font:11px Arial,sans-serif;color:#666;margin:0 0 6px">{escape(meta)}</div>'
        f'<table style="border-collapse:collapse;border:1px solid #ccc">'
        f'<thead><tr>{top}</tr><tr>{sub_row}</tr></thead>'
        f'<tbody>{body}</tbody></table>{notes}'
    )


def render_html_summary(report: ProjectNightReport) -> str:
    """Render the full email-body HTML for a project's night report."""
    windows_desc = ", ".join(w.label for w in (report.locations[0].windows if report.locations else []))
    header = (
        f'<h2 style="font:bold 18px Arial,sans-serif;margin:0 0 2px">'
        f'{escape(report.project_name)} — Night Report</h2>'
        f'<div style="font:13px Arial,sans-serif;color:#444;margin:0 0 4px">'
        f'Night of {report.night_date:%a %m/%d/%y} &nbsp;·&nbsp; last night vs. baseline</div>'
        f'<div style="font:11px Arial,sans-serif;color:#888;margin:0 0 10px">'
        f'Windows: {escape(windows_desc)}. '
        f'&Delta; = last night minus baseline (<span style="color:{_RED}">+ louder</span>, '
        f'<span style="color:{_GREEN}">− quieter</span>). '
        f'LAmax = loudest interval; L-values are arithmetic averages; '
        f'baseline = typical night.</div>'
    )

    if not report.locations:
        body = ('<div style="font:13px Arial,sans-serif;color:#b00020">'
                'No sound locations found for this project.</div>')
    else:
        body = ''.join(_location_table(loc) for loc in report.locations)

    footer = ('<div style="font:10px Arial,sans-serif;color:#aaa;margin-top:18px">'
              'Automated report — Terra-View. Full interval data in the attached spreadsheet.</div>')

    return (f'<!DOCTYPE html><html><body style="margin:0;padding:16px;background:#fff">'
            f'{header}{body}{footer}</body></html>')