from __future__ import annotations

import colorsys
import re
import tempfile
from pathlib import Path

import rrdtool

from .data import Sample

RRD_ERROR = rrdtool.OperationalError

STEP = 600
HEARTBEAT = 1500
SAFE_NAME = re.compile(r"^[a-z][a-z0-9_]*$")

SCHEMAS = {
    "outdoor": {"min_temp": "GAUGE:-60:70", "max_temp": "GAUGE:-60:70", "humidity": "GAUGE:0:100", "pressure": "GAUGE:800:1200"},
    "wind": {"gust": "GAUGE:0:300", "average": "GAUGE:0:300", "angle": "GAUGE:0:360"},
    "bedroom": {"temperature": "GAUGE:-20:60", "co2": "GAUGE:0:10000", "humidity": "GAUGE:0:100"},
    "study": {"temperature": "GAUGE:-20:60", "co2": "GAUGE:0:10000", "humidity": "GAUGE:0:100"},
    "living": {"temperature": "GAUGE:-20:60", "co2": "GAUGE:0:10000", "humidity": "GAUGE:0:100"},
}

PERIODS = {"day": ("1 day", "-1d"), "2weeks": ("2 weeks", "-14d"), "year": ("1 year", "-1y")}
ALIASES = {"1day": "day", "14days": "2weeks", "2week": "2weeks", "1year": "year"}


class RRDStore:
    def __init__(self, folder: Path, width: int = 900, height: int = 240):
        self.folder = Path(folder)
        self.width = width
        self.height = height

    def path(self, name: str) -> Path:
        if name not in SCHEMAS:
            raise KeyError(name)
        return self.folder / f"netatmo_{name}.rrd"

    def ensure_all(self) -> None:
        self.folder.mkdir(parents=True, exist_ok=True)
        for name, schema in SCHEMAS.items():
            path = self.path(name)
            if path.exists():
                continue
            # Leave room for a station that has been temporarily offline when the
            # RRD is first created; RRDtool rejects samples older than --start.
            args = ["--step", str(STEP), "--start", "now-1d"]
            args += [f"DS:{field}:{definition.split(':', 1)[0]}:{HEARTBEAT}:{definition.split(':', 1)[1]}" for field, definition in schema.items()]
            # 10-minute points for 2 weeks; 6-hour averages for over a year.
            args += ["RRA:AVERAGE:0.5:1:2016", "RRA:MIN:0.5:1:2016", "RRA:MAX:0.5:1:2016",
                     "RRA:AVERAGE:0.5:36:1464", "RRA:MIN:0.5:36:1464", "RRA:MAX:0.5:36:1464"]
            rrdtool.create(str(path), *args)

    def update(self, name: str, sample: Sample) -> None:
        schema = SCHEMAS[name]
        fields = list(schema)
        values = ["U" if sample.values.get(field) is None else str(sample.values[field]) for field in fields]
        rrdtool.update(
            str(self.path(name)),
            "--template", ":".join(fields),
            f"{sample.timestamp}:{':'.join(values)}",
        )

    def last(self, name: str, field: str) -> dict:
        if name not in SCHEMAS or field not in SCHEMAS[name]:
            raise KeyError(f"{name}/{field}")
        latest = rrdtool.lastupdate(str(self.path(name)))
        value = latest["ds"][field]
        return {
            "rrd": name,
            "data_point": field,
            "timestamp": int(latest["date"].timestamp()),
            "value": None if value is None else float(value),
        }

    def graph(self, name: str, period: str) -> bytes:
        period = ALIASES.get(period, period)
        if name not in SCHEMAS or period not in PERIODS:
            raise KeyError(f"{name}/{period}")
        title, start = PERIODS[period]
        common = ["--imgformat", "PNG", "--start", start, "--end", "now",
                  "--width", str(self.width), "--height", str(self.height), "--title", f"{name.title()} - {title}",
                  "--slope-mode", "--watermark", "GetNetatmoData v2"]
        definitions = [f"DEF:{field}={self.path(name)}:{field}:AVERAGE" for field in SCHEMAS[name]]
        if name == "wind":
            drawings = self._wind_drawings()
        elif name == "outdoor":
            drawings = ["LINE2:min_temp#3488DB:Minimum temperature (C)", "LINE2:max_temp#E74C3C:Maximum temperature (C)",
                        "LINE1:humidity#27AE60:Humidity (%)", "LINE1:pressure#8E44AD:Pressure (hPa):dashes"]
        else:
            drawings = ["LINE2:temperature#E74C3C:Temperature (C)", "LINE1:co2#8E44AD:CO2 (ppm)", "LINE1:humidity#27AE60:Humidity (%):dashes"]
        # The Python binding returns graph metadata, not the encoded image, so
        # render to an isolated temporary file and return its contents.
        with tempfile.TemporaryDirectory(prefix="netatmo-graph-") as folder:
            image_path = Path(folder) / f"{name}-{period}.png"
            rrdtool.graph(str(image_path), *(common + definitions + drawings))
            return image_path.read_bytes()

    @staticmethod
    def _wind_drawings() -> list[str]:
        result: list[str] = []
        # Split average wind into 12 angle bands. Each AREA starts at zero and
        # only exists for its direction, producing rainbow-colored bars/areas.
        for index in range(12):
            low, high = index * 30, (index + 1) * 30
            color = "#%02X%02X%02X80" % tuple(round(channel * 255) for channel in colorsys.hsv_to_rgb(index / 12, .85, .9))
            result += [f"CDEF:dir{index}=angle,{low},GE,angle,{high},LT,*,average,UNKN,IF", f"AREA:dir{index}{color}:{low:03d}-{high:03d} degrees"]
        result += ["LINE2:gust#111111:Gust", "LINE1:average#555555:Average"]
        return result