"""
piNail2 — Flask Web Application

Main entry point. Runs the Flask web server and initializes the PID controller.
Provides REST API endpoints and serves the single-page dashboard.

Usage:
    python3 app.py
    python3 app.py --config /path/to/config.json
"""

import sys
import os
import signal
import atexit
import logging
import argparse
import json
import time
import threading
import copy
from datetime import datetime

from flask import Flask, render_template, jsonify, request

from config import Config
from thermocouple import Thermocouple
from pid_controller import PIDController

# ---------------------------------------------------------------------------
# Logging setup
# ---------------------------------------------------------------------------
logging.basicConfig(
    level=logging.INFO,
    format="%(asctime)s [%(levelname)s] %(name)s: %(message)s",
    handlers=[
        logging.StreamHandler(sys.stdout),
    ]
)
log = logging.getLogger("piNail2")
APP_INSTANCE_ID = str(int(time.time()))
APP_VERSION = "v2.1.0"

# ---------------------------------------------------------------------------
# Flask app
# ---------------------------------------------------------------------------
app = Flask(__name__)

# These are set in main() before the app starts
config = None       # type: Config
controllers = {}
thermocouples = {}
channel_configs = {}

NAIL_IDS = ("nail1", "nail2")
CONFIG_WRITE_LOCK = threading.Lock()

CONTROL_LIMITS = {
    "loop_size_ms": {"min": 1500, "max": 5000},
    "sleep_time": {"min": 0.15, "max": 0.6},
}

PID_GUARDRAILS = {
    "balanced": {"kP_max": 80.0, "kI_max": 4.0, "kD_max": 50.0},
    "responsive": {"kP_max": 50.0, "kI_max": 2.5, "kD_max": 25.0},
    "extreme": {"kP_max": 35.0, "kI_max": 1.8, "kD_max": 15.0},
}


def classify_timing_profile(loop_size_ms, sleep_time):
    """Classify timing aggressiveness for safety guardrails."""
    if loop_size_ms <= 1400 or sleep_time <= 0.14:
        return "extreme"
    if loop_size_ms <= 1800 or sleep_time <= 0.20:
        return "responsive"
    if loop_size_ms <= 2800 or sleep_time <= 0.32:
        return "balanced"
    return "conservative"


def clamp_pid_for_profile(profile, pid_status):
    """Clamp PID gains to guardrails for aggressive timing profiles."""
    limits = PID_GUARDRAILS.get(profile)
    if not limits:
        return None

    before = {
        "kP": float(pid_status.get("kP", 0.0)),
        "kI": float(pid_status.get("kI", 0.0)),
        "kD": float(pid_status.get("kD", 0.0)),
    }
    after = {
        "kP": min(before["kP"], limits["kP_max"]),
        "kI": min(before["kI"], limits["kI_max"]),
        "kD": min(before["kD"], limits["kD_max"]),
    }

    changed = (
        abs(before["kP"] - after["kP"]) > 1e-9
        or abs(before["kI"] - after["kI"]) > 1e-9
        or abs(before["kD"] - after["kD"]) > 1e-9
    )
    if not changed:
        return None

    return {
        "before": before,
        "after": after,
        "limits": limits,
    }


def normalize_nail_id(raw_nail):
    if raw_nail is None:
        return "nail1"
    text = str(raw_nail).strip().lower()
    if text in ("1", "nail1"):
        return "nail1"
    if text in ("2", "nail2"):
        return "nail2"
    return None


def resolve_nail_id(body=None):
    q_nail = request.args.get("nail")
    if q_nail is not None:
        nail_id = normalize_nail_id(q_nail)
        if nail_id:
            return nail_id
    if body and "nail" in body:
        nail_id = normalize_nail_id(body.get("nail"))
        if nail_id:
            return nail_id
    return "nail1"


def get_nail_parts(nail_id):
    controller = controllers.get(nail_id)
    tc = thermocouples.get(nail_id)
    ch_cfg = channel_configs.get(nail_id)
    if controller is None or tc is None or ch_cfg is None:
        return None, None, None
    return controller, tc, ch_cfg


def ensure_nails_config(base_config):
    nails = base_config.get("nails")
    if isinstance(nails, dict) and "nail1" in nails and "nail2" in nails:
        return

    data = base_config.data
    default_nails = copy.deepcopy(data.get("nails", {}))
    nail1 = default_nails.get("nail1", {})
    nail2 = default_nails.get("nail2", {})
    for section in ("pid", "control", "flight", "scheduler", "safety", "logging", "autotune"):
        if section in data:
            nail1[section] = copy.deepcopy(data[section])
    if "gpio" in data:
        gpio1 = copy.deepcopy(data["gpio"])
        gpio2 = copy.deepcopy(nail2.get("gpio", {}))
        nail1["gpio"] = gpio1
        nail2["gpio"] = {
            "relay_pin": gpio2.get("relay_pin", 9),
            "clk": gpio2.get("clk", 17),
            "cs": gpio2.get("cs", 18),
            "do": gpio2.get("do", 27),
        }

    default_nails["nail1"] = nail1
    default_nails["nail2"] = nail2
    base_config._data["nails"] = default_nails
    base_config.save()


class ChannelConfigProxy:
    def __init__(self, root_config, nail_id):
        self._root = root_config
        self._nail_id = nail_id

    def _channel_dict(self):
        nails = self._root._data.setdefault("nails", {})
        return nails.setdefault(self._nail_id, {})

    def get(self, section, key=None):
        section_data = self._root._data.get("nails", {}).get(self._nail_id, {}).get(section)
        if section_data is None:
            section_data = self._root.get(section)
        if key is None:
            return copy.deepcopy(section_data if isinstance(section_data, dict) else {})
        return copy.deepcopy((section_data or {}).get(key))

    def set(self, section, key, value):
        with CONFIG_WRITE_LOCK:
            section_data = self._channel_dict().setdefault(section, {})
            section_data[key] = value
            self._root.save()

    def update_section(self, section, values):
        with CONFIG_WRITE_LOCK:
            section_data = self._channel_dict().setdefault(section, {})
            section_data.update(values)
            self._root.save()

    def reload_if_changed(self):
        return self._root.reload_if_changed()

# ---------------------------------------------------------------------------
# Routes — Pages
# ---------------------------------------------------------------------------

@app.route("/")
def index():
    """Serve the main dashboard."""
    return render_template(
        "index.html",
        app_version=APP_VERSION,
        copyright_year=datetime.now().year,
    )


# ---------------------------------------------------------------------------
# Routes — API
# ---------------------------------------------------------------------------

@app.route("/api/status")
def api_status():
    """Return current controller state."""
    nail_id = resolve_nail_id()
    controller, tc, ch_cfg = get_nail_parts(nail_id)
    if controller is None:
        return jsonify({"error": "Unknown nail"}), 404
    status = controller.status
    status["nail"] = nail_id
    status["instance_id"] = APP_INSTANCE_ID
    status["thermocouple"] = tc.stats
    status["presets"] = config.get("presets")
    status["config"] = {
        "loop_size_ms": ch_cfg.get("control", "loop_size_ms"),
        "sleep_time": ch_cfg.get("control", "sleep_time"),
        "safety": ch_cfg.get("safety"),
    }
    return jsonify(status)


@app.route("/api/status/all")
def api_status_all():
    payload = {
        "instance_id": APP_INSTANCE_ID,
        "presets": config.get("presets"),
        "nails": {},
    }
    for nail_id in NAIL_IDS:
        controller, tc, ch_cfg = get_nail_parts(nail_id)
        if controller is None:
            continue
        status = controller.status
        status["nail"] = nail_id
        status["thermocouple"] = tc.stats
        status["config"] = {
            "loop_size_ms": ch_cfg.get("control", "loop_size_ms"),
            "sleep_time": ch_cfg.get("control", "sleep_time"),
            "safety": ch_cfg.get("safety"),
        }
        payload["nails"][nail_id] = status
    return jsonify(payload)


@app.route("/api/heartbeat")
def api_heartbeat():
    """Lightweight health endpoint for frontend reconnect logic."""
    return jsonify({
        "ok": True,
        "instance_id": APP_INSTANCE_ID,
        "ts": time.time(),
        "controller_alive": {n: controllers[n].is_alive for n in controllers},
        "watchdog_ok": {n: controllers[n].watchdog_ok for n in controllers},
    })


@app.route("/api/history")
def api_history():
    """Return recent temperature history for charting."""
    nail_id = resolve_nail_id()
    controller, _, _ = get_nail_parts(nail_id)
    if controller is None:
        return jsonify({"error": "Unknown nail"}), 404
    since = request.args.get("since", 0, type=float)
    if since > 0:
        data = controller.get_history_since(since)
    else:
        data = controller.history
    return jsonify(data)


@app.route("/api/power", methods=["POST"])
def api_power():
    """Toggle controller on/off."""
    body = request.get_json(force=True, silent=True) or {}
    nail_id = resolve_nail_id(body)
    controller, _, _ = get_nail_parts(nail_id)
    if controller is None:
        return jsonify({"error": "Unknown nail"}), 404
    enable = body.get("enabled")

    if enable is None:
        # Toggle
        enable = not controller.status["enabled"]

    controller.set_power(enable)

    return jsonify({"enabled": enable, "ok": True, "nail": nail_id})


@app.route("/api/setpoint", methods=["POST"])
def api_setpoint():
    """Change the target temperature."""
    body = request.get_json(force=True, silent=True) or {}
    nail_id = resolve_nail_id(body)
    controller, _, ch_cfg = get_nail_parts(nail_id)
    if controller is None:
        return jsonify({"error": "Unknown nail"}), 404
    value = body.get("setpoint")
    if value is None:
        return jsonify({"error": "Missing 'setpoint' field"}), 400

    try:
        value = float(value)
    except (TypeError, ValueError):
        return jsonify({"error": "Invalid setpoint value"}), 400

    safety = ch_cfg.get("safety")
    if value > safety["max_temp_f"]:
        return jsonify({"error": "Setpoint {} exceeds max {}F".format(value, safety['max_temp_f'])}), 400
    if value < safety["min_temp_f"]:
        return jsonify({"error": "Setpoint {} below min {}F".format(value, safety['min_temp_f'])}), 400

    controller.set_setpoint(value)
    return jsonify({"setpoint": value, "ok": True, "nail": nail_id})


@app.route("/api/control", methods=["POST"])
def api_control():
    """Update loop timing controls (loop_size_ms and sleep_time)."""
    body = request.get_json(force=True, silent=True) or {}
    nail_id = resolve_nail_id(body)
    controller, _, ch_cfg = get_nail_parts(nail_id)
    if controller is None:
        return jsonify({"error": "Unknown nail"}), 404
    updates = {}
    confirm_extreme = bool(body.get("confirm_extreme", False))

    if "loop_size_ms" in body:
        try:
            loop_size_ms = int(body.get("loop_size_ms"))
        except (TypeError, ValueError):
            return jsonify({"error": "Invalid loop_size_ms"}), 400
        if loop_size_ms < CONTROL_LIMITS["loop_size_ms"]["min"] or loop_size_ms > CONTROL_LIMITS["loop_size_ms"]["max"]:
            return jsonify({
                "error": "loop_size_ms out of range",
                "min": CONTROL_LIMITS["loop_size_ms"]["min"],
                "max": CONTROL_LIMITS["loop_size_ms"]["max"],
            }), 400
        updates["loop_size_ms"] = loop_size_ms

    if "sleep_time" in body:
        try:
            sleep_time = float(body.get("sleep_time"))
        except (TypeError, ValueError):
            return jsonify({"error": "Invalid sleep_time"}), 400
        if sleep_time < CONTROL_LIMITS["sleep_time"]["min"] or sleep_time > CONTROL_LIMITS["sleep_time"]["max"]:
            return jsonify({
                "error": "sleep_time out of range",
                "min": CONTROL_LIMITS["sleep_time"]["min"],
                "max": CONTROL_LIMITS["sleep_time"]["max"],
            }), 400
        updates["sleep_time"] = sleep_time

    if not updates:
        return jsonify({"error": "No control fields provided"}), 400

    current_loop = ch_cfg.get("control", "loop_size_ms")
    current_sleep = ch_cfg.get("control", "sleep_time")
    new_loop = updates.get("loop_size_ms", current_loop)
    new_sleep = updates.get("sleep_time", current_sleep)

    profile = classify_timing_profile(new_loop, new_sleep)
    if profile == "extreme" and not confirm_extreme:
        return jsonify({
            "error": "Extreme timing requires confirm_extreme=true",
            "profile": profile,
            "control": {
                "loop_size_ms": new_loop,
                "sleep_time": new_sleep,
            },
        }), 400

    ch_cfg.update_section("control", updates)

    pid_status = controller.status.get("pid", {})
    clamp_info = clamp_pid_for_profile(profile, pid_status)
    if clamp_info:
        mode = pid_status.get("proportional_mode", "error")
        controller.set_pid_tuning(
            clamp_info["after"]["kP"],
            clamp_info["after"]["kI"],
            clamp_info["after"]["kD"],
            None,
            mode,
        )

    return jsonify({
        "ok": True,
        "control": {
            "loop_size_ms": ch_cfg.get("control", "loop_size_ms"),
            "sleep_time": ch_cfg.get("control", "sleep_time"),
        },
        "nail": nail_id,
        "profile": profile,
        "pid_clamped": bool(clamp_info),
        "pid_guardrail": clamp_info,
        "limits": CONTROL_LIMITS,
    })


@app.route("/api/flight", methods=["POST"])
def api_flight():
    """Update flight behavior settings and optional mode transition."""
    body = request.get_json(force=True, silent=True) or {}
    nail_id = resolve_nail_id(body)
    controller, _, _ = get_nail_parts(nail_id)
    if controller is None:
        return jsonify({"error": "Unknown nail"}), 404

    takeoff_seconds = body.get("takeoff_seconds")
    descent_seconds = body.get("descent_seconds")
    turbo = body.get("turbo")
    descent_target_f = body.get("descent_target_f")
    mode = body.get("mode")

    if takeoff_seconds is not None:
        try:
            takeoff_seconds = float(takeoff_seconds)
        except (TypeError, ValueError):
            return jsonify({"error": "Invalid takeoff_seconds"}), 400
        if takeoff_seconds < 5 or takeoff_seconds > 1800:
            return jsonify({"error": "takeoff_seconds out of range (5-1800)"}), 400

    if descent_seconds is not None:
        try:
            descent_seconds = float(descent_seconds)
        except (TypeError, ValueError):
            return jsonify({"error": "Invalid descent_seconds"}), 400
        if descent_seconds < 5 or descent_seconds > 1800:
            return jsonify({"error": "descent_seconds out of range (5-1800)"}), 400

    if descent_target_f is not None:
        try:
            descent_target_f = float(descent_target_f)
        except (TypeError, ValueError):
            return jsonify({"error": "Invalid descent_target_f"}), 400

    controller.set_flight_config(
        takeoff_seconds=takeoff_seconds,
        descent_seconds=descent_seconds,
        turbo=turbo,
        descent_target_f=descent_target_f,
    )

    if mode == "takeoff":
        controller.start_takeoff()
    elif mode == "cruise":
        controller.start_cruise()
    elif mode == "descent":
        controller.start_descent()
    elif mode == "grounded":
        controller.set_power(False)

    return jsonify({"ok": True, "status": controller.status, "nail": nail_id})


@app.route("/api/scheduler", methods=["POST"])
def api_scheduler():
    """Update daily cutoff scheduler settings."""
    body = request.get_json(force=True, silent=True) or {}
    nail_id = resolve_nail_id(body)
    controller, _, _ = get_nail_parts(nail_id)
    if controller is None:
        return jsonify({"error": "Unknown nail"}), 404
    enabled = body.get("enabled")
    cutoff_times = body.get("cutoff_times")

    if cutoff_times is not None:
        if not isinstance(cutoff_times, list):
            return jsonify({"error": "cutoff_times must be a list of HH:MM strings"}), 400
        normalized = []
        for t in cutoff_times:
            if not isinstance(t, str) or len(t) != 5 or t[2] != ":":
                return jsonify({"error": "Invalid time '{}'; expected HH:MM".format(t)}), 400
            hh, mm = t.split(":", 1)
            if not hh.isdigit() or not mm.isdigit():
                return jsonify({"error": "Invalid time '{}'; expected HH:MM".format(t)}), 400
            hhv = int(hh)
            mmv = int(mm)
            if hhv < 0 or hhv > 23 or mmv < 0 or mmv > 59:
                return jsonify({"error": "Invalid time '{}'; expected HH:MM".format(t)}), 400
            normalized.append("{:02d}:{:02d}".format(hhv, mmv))
        cutoff_times = sorted(list(set(normalized)))

    controller.set_scheduler(enabled=enabled, cutoff_times=cutoff_times)
    return jsonify({"ok": True, "scheduler": controller.status.get("scheduler"), "nail": nail_id})


@app.route("/api/pid", methods=["POST"])
def api_pid():
    """Update PID tuning parameters."""
    body = request.get_json(force=True, silent=True) or {}
    nail_id = resolve_nail_id(body)
    controller, _, _ = get_nail_parts(nail_id)
    if controller is None:
        return jsonify({"error": "Unknown nail"}), 404

    kp = body.get("kP")
    ki = body.get("kI")
    kd = body.get("kD")
    p_on_m = body.get("proportional_on_measurement")
    p_mode = body.get("proportional_mode")

    if kp is None or ki is None or kd is None:
        return jsonify({"error": "Missing kP, kI, or kD"}), 400

    try:
        kp, ki, kd = float(kp), float(ki), float(kd)
    except (TypeError, ValueError):
        return jsonify({"error": "Invalid PID values"}), 400

    controller.set_pid_tuning(kp, ki, kd, p_on_m, p_mode)
    mode_out = "measurement" if controller.status["pid"]["proportional_on_measurement"] else "error"
    return jsonify({
        "kP": kp,
        "kI": ki,
        "kD": kd,
        "nail": nail_id,
        "proportional_on_measurement": controller.status["pid"]["proportional_on_measurement"],
        "proportional_mode": mode_out,
        "ok": True,
    })


@app.route("/api/preset/<name>", methods=["POST"])
def api_preset(name):
    """Apply a named temperature preset."""
    body = request.get_json(force=True, silent=True) or {}
    nail_id = resolve_nail_id(body)
    controller, _, _ = get_nail_parts(nail_id)
    if controller is None:
        return jsonify({"error": "Unknown nail"}), 404
    presets = config.get("presets")
    if name not in presets:
        return jsonify({"error": "Unknown preset '{}'".format(name), "available": list(presets.keys())}), 404

    value = presets[name]
    controller.set_setpoint(value)
    return jsonify({"preset": name, "setpoint": value, "ok": True, "nail": nail_id})


@app.route("/api/presets", methods=["GET"])
def api_presets():
    """List all presets."""
    return jsonify(config.get("presets"))


@app.route("/api/presets", methods=["POST"])
def api_presets_update():
    """Add or update a preset."""
    body = request.get_json(force=True, silent=True) or {}
    name = body.get("name")
    value = body.get("setpoint")
    if not name or value is None:
        return jsonify({"error": "Missing 'name' or 'setpoint'"}), 400
    try:
        value = float(value)
    except (TypeError, ValueError):
        return jsonify({"error": "Invalid setpoint value"}), 400

    presets = config.get("presets")
    presets[name] = value
    config.update_section("presets", presets)
    return jsonify({"ok": True, "presets": presets})


@app.route("/api/presets/<name>", methods=["DELETE"])
def api_preset_delete(name):
    """Delete a preset."""
    presets = config.get("presets")
    if name not in presets:
        return jsonify({"error": "Unknown preset '{}'".format(name)}), 404
    del presets[name]
    # Overwrite entire presets section
    config._data["presets"] = presets
    config.save()
    return jsonify({"ok": True, "presets": presets})


@app.route("/api/config", methods=["GET"])
def api_config():
    """Return full config (read-only view)."""
    return jsonify(config.data)


@app.route("/api/pid/reset", methods=["POST"])
def api_pid_reset():
    """Reset PID controller internals (clears integral windup)."""
    body = request.get_json(force=True, silent=True) or {}
    nail_id = resolve_nail_id(body)
    controller, _, _ = get_nail_parts(nail_id)
    if controller is None:
        return jsonify({"error": "Unknown nail"}), 404
    controller._pid.reset()
    return jsonify({"ok": True, "message": "PID reset", "nail": nail_id})


@app.route("/api/autotune", methods=["GET"])
def api_autotune_status():
    """Return current autotune state."""
    nail_id = resolve_nail_id()
    controller, _, _ = get_nail_parts(nail_id)
    if controller is None:
        return jsonify({"error": "Unknown nail"}), 404
    payload = controller.autotune_status
    payload["nail"] = nail_id
    return jsonify(payload)


@app.route("/api/autotune/start", methods=["POST"])
def api_autotune_start():
    """Start relay-based PID autotune."""
    body = request.get_json(force=True, silent=True) or {}
    nail_id = resolve_nail_id(body)
    controller, _, _ = get_nail_parts(nail_id)
    if controller is None:
        return jsonify({"error": "Unknown nail"}), 404
    if not controller.status.get("enabled"):
        controller.start()
        time.sleep(0.2)
    setpoint = body.get("setpoint")
    hysteresis = body.get("hysteresis")
    cycles = body.get("cycles")
    controller.start_autotune(setpoint=setpoint, hysteresis=hysteresis, cycles=cycles)
    return jsonify({"ok": True, "autotune": controller.autotune_status, "nail": nail_id})


@app.route("/api/autotune/stop", methods=["POST"])
def api_autotune_stop():
    """Stop PID autotune."""
    body = request.get_json(force=True, silent=True) or {}
    nail_id = resolve_nail_id(body)
    controller, _, _ = get_nail_parts(nail_id)
    if controller is None:
        return jsonify({"error": "Unknown nail"}), 404
    controller.stop_autotune("Autotune stopped by user")
    return jsonify({"ok": True, "autotune": controller.autotune_status, "nail": nail_id})


@app.route("/api/safety/reset", methods=["POST"])
def api_safety_reset():
    """Reset safety trip (clears the safety flag so controller can be restarted)."""
    body = request.get_json(force=True, silent=True) or {}
    nail_id = resolve_nail_id(body)
    controller, _, _ = get_nail_parts(nail_id)
    if controller is None:
        return jsonify({"error": "Unknown nail"}), 404
    controller._safety_tripped = False
    controller._safety_reason = ""
    return jsonify({"ok": True, "nail": nail_id})


# ---------------------------------------------------------------------------
# Main
# ---------------------------------------------------------------------------

def shutdown_handler(*args):
    """Handle SIGTERM/SIGINT gracefully."""
    log.info("Shutdown signal received")
    for nail_id in controllers:
        try:
            controllers[nail_id].cleanup()
        except Exception as e:
            log.error("Cleanup failed for %s: %s", nail_id, e)
    sys.exit(0)


def cleanup_all():
    for nail_id in controllers:
        try:
            controllers[nail_id].cleanup()
        except Exception as e:
            log.error("Cleanup failed for %s: %s", nail_id, e)


def main():
    global config

    parser = argparse.ArgumentParser(description="piNail2 — E-Nail Temperature Controller")
    parser.add_argument("--config", default="config.json", help="Path to config file")
    args = parser.parse_args()

    # Load config
    config = Config(args.config)
    log.info("Configuration loaded from %s", args.config)
    ensure_nails_config(config)

    for nail_id in NAIL_IDS:
        ch_cfg = ChannelConfigProxy(config, nail_id)
        channel_configs[nail_id] = ch_cfg
        gpio_cfg = ch_cfg.get("gpio")
        safety_cfg = ch_cfg.get("safety")
        tc = Thermocouple(
            clk=gpio_cfg["clk"],
            cs=gpio_cfg["cs"],
            do=gpio_cfg["do"],
            spike_threshold=safety_cfg["spike_threshold_f"]
        )
        thermocouples[nail_id] = tc

        controller = PIDController(ch_cfg, tc)
        controller.start_monitoring()
        controllers[nail_id] = controller
        log.info("Initialized %s (relay pin %s)", nail_id, gpio_cfg.get("relay_pin"))

    # Register cleanup
    signal.signal(signal.SIGTERM, shutdown_handler)
    signal.signal(signal.SIGINT, shutdown_handler)
    atexit.register(cleanup_all)

    # Start Flask
    web_cfg = config.get("web")
    log.info("Starting web server on %s:%d", web_cfg["host"], web_cfg["port"])
    app.run(
        host=web_cfg["host"],
        port=web_cfg["port"],
        debug=False,
        threaded=True
    )


if __name__ == "__main__":
    main()