"""
Charts Router - Chart.js-compatible Data Endpoints

Provides structured data for frontend charts/diagrams.

All endpoints return Chart.js-compatible JSON format:
{
    "chart_type": "line" | "bar" | "scatter" | "pie",
    "data": {
        "labels": [...],
        "datasets": [...]
    },
    "metadata": {
        "confidence": "high" | "medium" | "low" | "insufficient",
        "data_points": int,
        ...
    }
}

Phase 0c: Multi-Layer Architecture
Version: 1.0
"""

from fastapi import APIRouter, Depends, HTTPException, Query
from typing import Dict, List, Optional
from datetime import datetime, timedelta

from auth import require_auth
from data_layer.body_metrics import (
    get_weight_trend_data,
    get_body_composition_data,
    get_circumference_summary_data
)
from data_layer.utils import serialize_dates

router = APIRouter()


# ── Body Charts ─────────────────────────────────────────────────────────────


@router.get("/charts/weight-trend")
def get_weight_trend_chart(
    days: int = Query(default=90, ge=7, le=365, description="Analysis window in days"),
    session: dict = Depends(require_auth)
) -> Dict:
    """
    Weight trend chart data.

    Returns Chart.js-compatible line chart with:
    - Raw weight values
    - Trend line (if enough data)
    - Confidence indicator

    Args:
        days: Analysis window (7-365 days, default 90)
        session: Auth session (injected)

    Returns:
        {
            "chart_type": "line",
            "data": {
                "labels": ["2026-01-01", ...],
                "datasets": [{
                    "label": "Gewicht",
                    "data": [85.0, 84.5, ...],
                    "borderColor": "#1D9E75",
                    "backgroundColor": "rgba(29, 158, 117, 0.1)",
                    "tension": 0.4
                }]
            },
            "metadata": {
                "confidence": "high",
                "data_points": 60,
                "first_value": 92.0,
                "last_value": 85.0,
                "delta": -7.0,
                "direction": "decreasing"
            }
        }

    Metadata fields:
        - confidence: Data quality ("high", "medium", "low", "insufficient")
        - data_points: Number of weight entries in period
        - first_value: First weight in period (kg)
        - last_value: Latest weight (kg)
        - delta: Weight change (kg, negative = loss)
        - direction: "increasing" | "decreasing" | "stable"
    """
    profile_id = session['profile_id']

    # Get structured data from data layer
    trend_data = get_weight_trend_data(profile_id, days)

    # Early return if insufficient data
    if trend_data['confidence'] == 'insufficient':
        return {
            "chart_type": "line",
            "data": {
                "labels": [],
                "datasets": []
            },
            "metadata": {
                "confidence": "insufficient",
                "data_points": 0,
                "message": "Nicht genug Daten für Trend-Analyse"
            }
        }

    # Get raw data points for chart
    from db import get_db, get_cursor
    with get_db() as conn:
        cur = get_cursor(conn)
        cutoff = (datetime.now() - timedelta(days=days)).strftime('%Y-%m-%d')
        cur.execute(
            """SELECT date, weight FROM weight_log
               WHERE profile_id=%s AND date >= %s
               ORDER BY date""",
            (profile_id, cutoff)
        )
        rows = cur.fetchall()

    # Format for Chart.js
    labels = [row['date'].isoformat() for row in rows]
    values = [float(row['weight']) for row in rows]

    return {
        "chart_type": "line",
        "data": {
            "labels": labels,
            "datasets": [
                {
                    "label": "Gewicht",
                    "data": values,
                    "borderColor": "#1D9E75",
                    "backgroundColor": "rgba(29, 158, 117, 0.1)",
                    "borderWidth": 2,
                    "tension": 0.4,
                    "fill": True,
                    "pointRadius": 3,
                    "pointHoverRadius": 5
                }
            ]
        },
        "metadata": serialize_dates({
            "confidence": trend_data['confidence'],
            "data_points": trend_data['data_points'],
            "first_value": trend_data['first_value'],
            "last_value": trend_data['last_value'],
            "delta": trend_data['delta'],
            "direction": trend_data['direction'],
            "first_date": trend_data['first_date'],
            "last_date": trend_data['last_date'],
            "days_analyzed": trend_data['days_analyzed']
        })
    }


@router.get("/charts/body-composition")
def get_body_composition_chart(
    days: int = Query(default=90, ge=7, le=365),
    session: dict = Depends(require_auth)
) -> Dict:
    """
    Body composition chart (body fat percentage, lean mass trend).

    Returns Chart.js-compatible multi-line chart.

    Args:
        days: Analysis window (7-365 days, default 90)
        session: Auth session (injected)

    Returns:
        Chart.js format with datasets for:
        - Body fat percentage (%)
        - Lean mass (kg, if weight available)
    """
    profile_id = session['profile_id']

    # Get latest body composition
    comp_data = get_body_composition_data(profile_id, days)

    if comp_data['confidence'] == 'insufficient':
        return {
            "chart_type": "line",
            "data": {
                "labels": [],
                "datasets": []
            },
            "metadata": {
                "confidence": "insufficient",
                "data_points": 0,
                "message": "Keine Körperfett-Messungen vorhanden"
            }
        }

    # For PoC: Return single data point
    # TODO in bulk migration: Fetch historical caliper entries
    return {
        "chart_type": "line",
        "data": {
            "labels": [comp_data['date'].isoformat() if comp_data['date'] else ""],
            "datasets": [
                {
                    "label": "Körperfett %",
                    "data": [comp_data['body_fat_pct']],
                    "borderColor": "#D85A30",
                    "backgroundColor": "rgba(216, 90, 48, 0.1)",
                    "borderWidth": 2
                }
            ]
        },
        "metadata": serialize_dates({
            "confidence": comp_data['confidence'],
            "data_points": comp_data['data_points'],
            "body_fat_pct": comp_data['body_fat_pct'],
            "method": comp_data['method'],
            "date": comp_data['date']
        })
    }


@router.get("/charts/circumferences")
def get_circumferences_chart(
    max_age_days: int = Query(default=90, ge=7, le=365),
    session: dict = Depends(require_auth)
) -> Dict:
    """
    Latest circumference measurements as bar chart.

    Shows most recent measurement for each body point.

    Args:
        max_age_days: Maximum age of measurements (default 90)
        session: Auth session (injected)

    Returns:
        Chart.js bar chart with all circumference points
    """
    profile_id = session['profile_id']

    circ_data = get_circumference_summary_data(profile_id, max_age_days)

    if circ_data['confidence'] == 'insufficient':
        return {
            "chart_type": "bar",
            "data": {
                "labels": [],
                "datasets": []
            },
            "metadata": {
                "confidence": "insufficient",
                "data_points": 0,
                "message": "Keine Umfangsmessungen vorhanden"
            }
        }

    # Sort by value (descending) for better visualization
    measurements = sorted(
        circ_data['measurements'],
        key=lambda m: m['value'],
        reverse=True
    )

    labels = [m['point'] for m in measurements]
    values = [m['value'] for m in measurements]

    return {
        "chart_type": "bar",
        "data": {
            "labels": labels,
            "datasets": [
                {
                    "label": "Umfang (cm)",
                    "data": values,
                    "backgroundColor": "#1D9E75",
                    "borderColor": "#085041",
                    "borderWidth": 1
                }
            ]
        },
        "metadata": serialize_dates({
            "confidence": circ_data['confidence'],
            "data_points": circ_data['data_points'],
            "newest_date": circ_data['newest_date'],
            "oldest_date": circ_data['oldest_date'],
            "measurements": circ_data['measurements']  # Full details
        })
    }


# ── Health Endpoint ──────────────────────────────────────────────────────────


@router.get("/charts/health")
def health_check() -> Dict:
    """
    Health check endpoint for charts API.

    Returns:
        {
            "status": "ok",
            "version": "1.0",
            "available_charts": [...]
        }
    """
    return {
        "status": "ok",
        "version": "1.0",
        "phase": "0c",
        "available_charts": [
            {
                "endpoint": "/charts/weight-trend",
                "type": "line",
                "description": "Weight trend over time"
            },
            {
                "endpoint": "/charts/body-composition",
                "type": "line",
                "description": "Body fat % and lean mass"
            },
            {
                "endpoint": "/charts/circumferences",
                "type": "bar",
                "description": "Latest circumference measurements"
            }
        ]
    }