#!/usr/bin/env python3
"""Generate system-monitor PNG graphs from its RRD database."""

from __future__ import annotations

import argparse
import configparser
import html
from pathlib import Path
import subprocess


PERIODS = {"3hours": "3h", "1day": "1d", "2weeks": "2w", "1year": "1y"}
COLORS = ["#2563EB", "#DC2626", "#16A34A", "#9333EA"]
LOAD_COLORS = ["#DC2626", "#F59E0B", "#FACC15"]  # red, amber, yellow


def graph(output: Path, rrd: Path, start: str, title: str, unit: str,
          series: list[tuple[str, str, str]], logarithmic: bool = False,
          stacked: bool = False, disk_memory: bool = False,
          network_mixed: bool = False) -> None:
    args = ["rrdtool", "graph", str(output), "--start", f"end-{start}",
            "--end", "now", "--width", "900", "--height", "260",
            "--title", title, "--vertical-label", unit, "--slope-mode",
            "--watermark", "cheap-system-monitor"]
    if logarithmic:
        args += ["--logarithmic", "--lower-limit", "1"]
    value_suffix = "%%" if unit == "%" else ""
    for index, (ds, label, cf) in enumerate(series):
        var = f"v{index}"
        if network_mixed and ds == "net_out":
            drawing = f"AREA:{var}#86EFAC:{label}"
        elif network_mixed and ds == "net_in":
            drawing = f"LINE3:{var}#2563EB:{label}"
        elif disk_memory and ds == "memory":
            drawing = f"LINE3:{var}#DC2626:{label}"
        elif disk_memory:
            # Transparency keeps multiple mountpoints visible when their
            # percentage areas overlap.
            drawing = f"AREA:{var}{COLORS[index % len(COLORS)]}80:{label}"
        elif stacked:
            stack = ":STACK" if index else ""
            stacked_colors = LOAD_COLORS if title.startswith("Processor load") else COLORS
            drawing = f"AREA:{var}{stacked_colors[index]}:{label}{stack}"
        else:
            drawing = f"LINE{2 if index < 3 else 1}:{var}{COLORS[index % len(COLORS)]}:{label}"
        args += [f"DEF:{var}={rrd}:{ds}:{cf}",
                 drawing,
                 f"GPRINT:{var}:LAST:Current\\:%8.2lf%s{value_suffix}",
                 f"GPRINT:{var}:AVERAGE:Average\\:%8.2lf%s{value_suffix}",
                 f"GPRINT:{var}:MAX:Maximum\\:%8.2lf%s{value_suffix}\\n"]
    subprocess.run(args, check=True)


def main() -> None:
    parser = argparse.ArgumentParser(description=__doc__)
    parser.add_argument("--config", default="/opt/cheap_system_monitor/monitor.conf")
    args = parser.parse_args()
    config_parser = configparser.ConfigParser()
    if not config_parser.read(args.config):
        raise SystemExit(f"Configuration file not found: {args.config}")
    config = config_parser["monitor"]
    rrd = Path(config["rrd_file"])
    if not rrd.exists():
        raise SystemExit(f"RRD file does not exist: {rrd}")
    output_dir = Path(config.get("graph_dir", "/var/www/html/system-monitor"))
    output_dir.mkdir(parents=True, exist_ok=True)
    mounts = [item.strip() for item in config["mountpoints"].split(",") if item.strip()]
    if not mounts or mounts[0] != "/":
        mounts.insert(0, "/")
    definitions = [
        ("load", "Processor load", "load", [("load1", "1 minute", "AVERAGE"), ("load5", "5 minutes", "AVERAGE"), ("load15", "15 minutes", "AVERAGE")], False, True, False, False),
        ("cpu", "CPU usage", "%", [("cpu_user", "user", "AVERAGE"), ("cpu_system", "system", "AVERAGE"), ("cpu_nice", "nice", "AVERAGE")], False, True, False, False),
        ("network", "Network throughput", "bytes/s", [("net_out", "sent", "AVERAGE"), ("net_in", "received", "AVERAGE")], False, False, False, True),
        ("disk", "Disk and memory usage", "%", [(f"disk_{'root' if i == 0 else i}", mount, "AVERAGE") for i, mount in enumerate(mounts)] + [("memory", "memory", "AVERAGE")], False, False, True, False),
        ("uptime", "System uptime", "days", [("uptime", "uptime", "AVERAGE")], False, False, False, False),
    ]
    for period_name, start in PERIODS.items():
        for filename, title, unit, series, logarithmic, stacked, disk_memory, network_mixed in definitions:
            graph(output_dir / f"{filename}-{period_name}.png", rrd, start,
                  f"{title} — {period_name}", unit, series, logarithmic,
                  stacked, disk_memory, network_mixed)
    page_files = {
        "3hours": "index.html",
        "1day": "1day.html",
        "2weeks": "2weeks.html",
        "1year": "1year.html",
    }
    period_labels = {
        "3hours": "3 hours",
        "1day": "1 day",
        "2weeks": "2 weeks",
        "1year": "1 year",
    }
    for period in PERIODS:
        cards = "\n".join(
            f'<section><h2>{html.escape(title)}</h2>'
            f'<img src="{filename}-{period}.png" '
            f'alt="{html.escape(title)}, {period_labels[period]}"></section>'
            for filename, title, *_rest in definitions
        )
        navigation = " ".join(
            f'<a href="{page_files[item]}"'
            f'{" class=active" if item == period else ""}>'
            f'{period_labels[item]}</a>'
            for item in PERIODS
        )
        page = f"""<!doctype html>
<html lang="en"><head><meta charset="utf-8"><meta name="viewport" content="width=device-width">
<meta http-equiv="refresh" content="300"><title>System monitor — {period_labels[period]}</title>
<style>body{{font:16px system-ui;margin:auto;max-width:1100px;padding:1rem;background:#f8fafc;color:#172033}}
nav{{display:flex;gap:.5rem;flex-wrap:wrap}} nav a{{padding:.5rem .75rem;background:#e2e8f0;color:#172033;text-decoration:none;border-radius:.35rem}}
nav a.active{{background:#2563eb;color:white}} section{{background:white;padding:1rem;margin:1rem 0;border-radius:.5rem;box-shadow:0 1px 4px #0002}}
img{{width:100%;height:auto}}</style>
</head><body><h1>System monitor — {period_labels[period]}</h1><nav>{navigation}</nav>{cards}</body></html>"""
        (output_dir / page_files[period]).write_text(page)


if __name__ == "__main__":
    main()