#!/usr/bin/env python3
"""Format timesheet completion data into a markdown report."""

from __future__ import annotations

import argparse
import json
import sys
from datetime import datetime, timezone
from pathlib import Path
from typing import Any


def fmt_h(hours: float) -> str:
    """Format hours with one decimal place, dropping .0 for whole numbers."""
    if hours == int(hours):
        return f"{int(hours)}h"
    return f"{hours:.1f}h"


def completion_badge(pct: float) -> str:
    if pct >= 100:
        return "✓"
    if pct >= 75:
        return ""
    if pct >= 50:
        return "⚠"
    return "⚠⚠"


def build_report(data: dict[str, Any]) -> str:
    period = data["period"]
    summary = data["summary"]
    employees = data["employees"]

    generated_at = datetime.now(timezone.utc).strftime("%Y-%m-%d %H:%M UTC")
    n = summary["total_employees"]
    per_person = fmt_h(summary["total_expected_hours"] / n) if n else "0h"

    wdays_by_country: dict[str, int] = period.get("working_days_by_country", {})
    if len(wdays_by_country) == 1:
        country, wdays = next(iter(wdays_by_country.items()))
        wdays_line = f"Working days: {wdays} ({country} calendar, public holidays excluded)"
    else:
        parts = ", ".join(f"{c}: {d}d" for c, d in sorted(wdays_by_country.items()))
        wdays_line = f"Working days by country: {parts} (public holidays excluded)"

    lines = [
        "# Timesheet Completion Report",
        "",
        f"Generated: {generated_at}",
        f"Period: {period['label'].capitalize()} ({period['start']} to {period['end']})",
        wdays_line,
        "",
        "## Summary",
        "",
        f"- Expected: **{fmt_h(summary['total_expected_hours'])}** ({n} employees × {per_person} avg)",
        f"- Reported: **{fmt_h(summary['total_reported_hours'])}**",
        f"- Overall completion: **{summary['overall_completion_pct']}%**",
        f"- Fully complete: {summary['employees_fully_complete']} of {n} employees",
        f"- With gaps: {summary['employees_with_gaps']} employees",
        "",
        "## Employees (ranked by missing hours)",
        "",
        "| Employee | Expected | Reported | Completion | Missing |",
        "| --- | ---: | ---: | ---: | ---: |",
    ]

    # Determine the most common working-day count to detect deviations
    max_wdays = max(wdays_by_country.values()) if wdays_by_country else 0
    for emp in employees:
        badge = completion_badge(emp["completion_pct"])
        missing = fmt_h(emp["missing_hours"]) if emp["missing_hours"] > 0 else "—"
        pct_str = f"{emp['completion_pct']}% {badge}".strip()
        name = emp["name"]
        notes = []
        eff = emp.get("effective_working_days", max_wdays)
        if emp.get("start_date") and eff < max_wdays:
            notes.append(f"from {emp['start_date']}")
        if emp.get("termination_date") and eff < max_wdays:
            notes.append(f"until {emp['termination_date']}")
        if len(wdays_by_country) > 1:
            notes.append(emp.get("country", ""))
        if notes:
            name += f" _({', '.join(n for n in notes if n)})_"
        lines.append(
            f"| {name} | {fmt_h(emp['expected_hours'])} "
            f"| {fmt_h(emp['reported_hours'])} | {pct_str} | {missing} |"
        )

    out_of_range = [
        emp for emp in employees
        if emp.get("hours_before_start", 0) > 0 or emp.get("hours_after_termination", 0) > 0
    ]
    if out_of_range:
        lines += [
            "",
            "## Hours logged outside employment period",
            "",
            "These hours are excluded from the completion calculation above.",
            "",
            "| Employee | Before start date | After termination date |",
            "| --- | ---: | ---: |",
        ]
        for emp in out_of_range:
            before = fmt_h(emp["hours_before_start"]) if emp.get("hours_before_start", 0) > 0 else "—"
            after = fmt_h(emp["hours_after_termination"]) if emp.get("hours_after_termination", 0) > 0 else "—"
            lines.append(f"| {emp['name']} | {before} | {after} |")

    countries_str = ", ".join(sorted(wdays_by_country.keys()))
    lines += [
        "",
        "---",
        "",
        f"_Working days source: [date.nager.at](https://date.nager.at) ({countries_str})._",
        "_Hours source: Tempo._",
    ]
    return "\n".join(lines) + "\n"


def run(args: argparse.Namespace) -> int:
    data_path = Path(args.data)
    if not data_path.exists():
        print(f"Error: {data_path} not found. Run preprocess.py first.", file=sys.stderr)
        return 1

    data = json.loads(data_path.read_text(encoding="utf-8"))
    output_dir = Path(args.output_dir)
    output_dir.mkdir(parents=True, exist_ok=True)

    report = build_report(data)
    report_path = output_dir / "timesheet_report.md"
    report_path.write_text(report, encoding="utf-8")
    print(f"Wrote {report_path}")
    return 0


def build_parser() -> argparse.ArgumentParser:
    parser = argparse.ArgumentParser(
        description="Format timesheet completion data into a markdown report."
    )
    parser.add_argument(
        "--data",
        required=True,
        help="Path to timesheet_data.json produced by preprocess.py.",
    )
    parser.add_argument(
        "--output-dir",
        required=True,
        help="Directory for timesheet_report.md.",
    )
    return parser


if __name__ == "__main__":
    sys.exit(run(build_parser().parse_args()))