import random
from dataclasses import dataclass, field
from datetime import date, datetime, time, timedelta
from typing import Optional

import pytz
from dateutil import parser

from ..coaching import BaseCurriculum, ScalarAttributeDefinition
from ..factory import ProceduralDataset, register_dataset


@dataclass
class TimeIntervalsConfig:
    """Configuration for time interval calculation tasks"""

    min_time: time = time.min
    max_time: time = time.max
    max_time_difference_seconds: int = 24 * 60 * 60
    min_date: date = date(1900, 1, 1)
    max_date: date = date(3000, 1, 1)
    max_date_difference_days: int = 100
    task_types: list[str] = field(
        default_factory=lambda: ["time", "time_seconds", "time_ms", "date", "datetime", "datetime_tz"]
    )
    seed: Optional[int] = None
    size: int = 500

    def validate(self) -> None:
        """Validate configuration parameters"""
        assert self.size > 0, "size must be positive"
        assert self.max_time_difference_seconds > 0, "max_time_difference_seconds must be positive"
        assert self.max_date_difference_days > 0, "max_date_difference_days must be positive"
        assert self.min_date < self.max_date, "min_date must be before max_date"


class TimeIntervalsDataset(ProceduralDataset):
    """Generates time interval calculation tasks with various formats and complexities"""

    TEMPLATES = [
        "What is the duration between {start} and {end}? Please answer in {format}.",
        "Calculate the time difference between {start} and {end}. Express the result in {format}.",
        "How much time elapsed from {start} to {end}? Give your answer in {format}.",
        "A meeting started at {start} and ended at {end}. How long was the meeting? Answer in {format}.",
        "A system operation started at {start} and completed at {end}. What was the operation duration? Answer in {format}.",
        "A database query started at {start} and ended at {end}. How long did the query take? Answer in {format}.",
        "A flight departed at {start} and arrived at {end}. How long was the flight? Answer in {format}.",
        "A video call started at {start} and ended at {end}. How long was the call? Answer in {format}.",
        "A system backup started at {start} and completed at {end}. What was the total backup duration? Answer in {format}.",
        "A conference call began at {start} and ended at {end}. How long was the conference? Answer in {format}.",
    ]

    TIME_FORMATS = [
        "%H:%M",
        "%H:%M:%S",
        "%H:%M:%S.%f",
    ]

    DATE_FORMATS = [
        "%Y-%m-%d",
        "%B %d, %Y",
        "%m/%d/%Y",
        "%A, %B %d, %Y",  # e.g. Monday, January 15, 2024
        "%a %b %d %Y",  # e.g. Mon Jan 15 2024
        "%d %B %Y",  # e.g. 15 January 2024
        "%Y-%m-%d (%A)",  # e.g. 2024-01-15 (Monday)
    ]

    DATETIME_FORMATS = [
        "%Y-%m-%d %H:%M",
        "%Y-%m-%d %H:%M:%S",
        "%Y-%m-%d %H:%M %z",  # For UTC offset format
        "%Y-%m-%d %H:%M:%S %z",  # For UTC offset with seconds
        "%A, %B %d, %Y at %H:%M",  # e.g. Monday, January 15, 2024 at 14:30
        "%a %b %d %Y %H:%M:%S",  # e.g. Mon Jan 15 2024 14:30:45
        "%d %B %Y, %H:%M",  # e.g. 15 January 2024, 14:30
        "%d %B %Y, %H:%M %z",  # e.g. 15 January 2024, 14:30 +0000
        "%Y-%m-%d (%A) %H:%M:%S %z",  # e.g. 2024-01-15 (Monday) 14:30:45 +0000
    ]

    def __init__(self, config: TimeIntervalsConfig):
        super().__init__(config=config, seed=config.seed, size=config.size)

    def __getitem__(self, idx: int) -> dict:
        """Generate a single time interval calculation task"""
        rng = random.Random(self.seed + idx)

        # Randomly choose task type from config
        task_type = rng.choice(self.config.task_types)

        start_time, end_time, format_str, expected_format = self._generate_times(rng, task_type)

        template = rng.choice(self.TEMPLATES)
        question = template.format(start=start_time, end=end_time, format=expected_format)

        # Calculate the actual difference
        if isinstance(start_time, str):
            # Handle datetime strings with weekday names in parentheses
            start_time = start_time.split(" (")[0]  # Remove (Weekday) if present
            end_time = end_time.split(" (")[0]
            # Parse with UTC offset handling
            start_dt = parser.parse(start_time)
            end_dt = parser.parse(end_time)
        else:
            start_dt = start_time
            end_dt = end_time

        difference = end_dt - start_dt

        # Format the answer according to expected_format
        if expected_format == "HH:MM":
            total_seconds = difference.total_seconds()
            answer = f"{int(total_seconds // 3600):02d}:{int((total_seconds % 3600) // 60):02d}"
        elif expected_format == "HH:MM:SS":
            total_seconds = difference.total_seconds()
            answer = f"{int(total_seconds // 3600):02d}:{int((total_seconds % 3600) // 60):02d}:{int(total_seconds % 60):02d}"
        elif expected_format == "HH:MM:SS.mmm":
            total_seconds = difference.total_seconds()
            ms = int((total_seconds % 1) * 1000)
            answer = f"{int(total_seconds // 3600):02d}:{int((total_seconds % 3600) // 60):02d}:{int(total_seconds % 60):02d}.{ms:03d}"
        elif expected_format == "D days":
            answer = f"{difference.days} days"
        else:  # "D days, HH:MM" or "D days, HH:MM:SS"
            days = difference.days
            hours = difference.seconds // 3600
            minutes = (difference.seconds % 3600) // 60
            seconds = difference.seconds % 60
            if expected_format == "D days, HH:MM:SS":
                answer = f"{days} days, {hours:02d}:{minutes:02d}:{seconds:02d}"
            else:  # "D days, HH:MM"
                answer = f"{days} days, {hours:02d}:{minutes:02d}"

        return {
            "question": question,
            "answer": answer,
            "metadata": {
                "task_type": task_type,
                "start_time": start_dt,
                "end_time": end_dt,
                "format": format_str,
                "expected_format": expected_format,
                "difficulty": {
                    "max_time_difference_seconds": self.config.max_time_difference_seconds,
                    "max_date_difference_days": self.config.max_date_difference_days,
                },
            },
        }

    def _generate_times(self, rng: random.Random, task_type: str):
        """Generate start and end times based on task type"""
        if task_type.startswith("time"):
            if task_type == "time_ms":
                format_str = self.TIME_FORMATS[2]  # Get milliseconds format
                expected_format = "HH:MM:SS.mmm"
            else:
                format_str = next(f for f in self.TIME_FORMATS if f.count(":") == (2 if "seconds" in task_type else 1))
                expected_format = "HH:MM:SS" if "seconds" in task_type else "HH:MM"

            # Generate random start time
            start_hour = rng.randint(0, 23)
            start_minute = rng.randint(0, 59)
            start_second = rng.randint(0, 59)
            base = datetime.combine(date.today(), time(start_hour, start_minute, start_second))

            # Calculate seconds remaining until midnight
            seconds_until_midnight = ((24 - start_hour) * 3600) - (start_minute * 60) - start_second
            # Use the minimum of config max and seconds until midnight
            max_seconds = min(self.config.max_time_difference_seconds, seconds_until_midnight)
            diff_seconds = rng.randint(1, max_seconds) if max_seconds > 0 else 0

            if task_type == "time_ms":
                # Add microseconds for millisecond precision
                base = base.replace(microsecond=rng.randint(0, 999) * 1000)
                end_time = base + timedelta(seconds=diff_seconds, microseconds=rng.randint(0, 999) * 1000)
                # Format with exactly 3 decimal places for milliseconds
                start_time = base.strftime(format_str)[:-3]  # Remove extra microsecond digits
                end_time = end_time.strftime(format_str)[:-3]  # Remove extra microsecond digits
            else:
                start_time = base.strftime(format_str)
                end_time = (base + timedelta(seconds=diff_seconds)).strftime(format_str)

        elif task_type == "date":
            format_str = rng.choice(self.DATE_FORMATS)
            expected_format = "D days"  # Always return number of days for date tasks

            # Generate random start date within configured range, leaving room for end date
            max_date_difference_days = min(
                self.config.max_date_difference_days, (self.config.max_date - self.config.min_date).days
            )
            max_start_days = (self.config.max_date - self.config.min_date).days - max_date_difference_days
            start_days = rng.randint(0, max_start_days - 1)
            start_date = self.config.min_date + timedelta(days=start_days)

            # Ensure positive difference between dates
            diff_days = rng.randint(0, max_date_difference_days)
            end_date = start_date + timedelta(days=diff_days)

            start_time = start_date.strftime(format_str)
            end_time = end_date.strftime(format_str)

        else:  # datetime or datetime_tz
            format_str = rng.choice(self.DATETIME_FORMATS)
            # Choose between HH:MM and HH:MM:SS format for datetime answers
            expected_format = rng.choice(["D days, HH:MM", "D days, HH:MM:SS"])

            # Generate random start datetime
            days_range = (self.config.max_date - self.config.min_date).days
            start_days = rng.randint(0, days_range)
            start_hour = rng.randint(0, 23)
            start_minute = rng.randint(0, 59)
            start_second = rng.randint(0, 59)

            # Generate random time differences first
            diff_days = rng.randint(0, self.config.max_date_difference_days)
            diff_seconds = rng.randint(1, self.config.max_time_difference_seconds)

            if "%z" in format_str:
                # Use simpler timezone format with offset
                base = datetime.combine(
                    self.config.min_date + timedelta(days=start_days), time(start_hour, start_minute, start_second)
                )
                # Generate timezone offsets
                start_offset = rng.randint(-12, 12)
                end_offset = rng.randint(-12, 12)

                # Apply start timezone
                base = base.replace(tzinfo=pytz.FixedOffset(start_offset * 60))
                start_format = format_str.replace("%z", "%+05d" % (start_offset * 100))

                # Calculate end time and convert to end timezone
                end_dt = base + timedelta(days=diff_days, seconds=diff_seconds)
                end_dt = end_dt.replace(tzinfo=pytz.FixedOffset(end_offset * 60))
                end_format = format_str.replace("%z", "%+05d" % (end_offset * 100))

                # Format times with their respective timezone offsets
                start_time = base.strftime(start_format).rstrip()
                end_time = end_dt.strftime(end_format).rstrip()
            else:
                base = datetime.combine(
                    self.config.min_date + timedelta(days=start_days), time(start_hour, start_minute, start_second)
                )
                # For non-timezone aware times, both use same format
                start_time = base.strftime(format_str).rstrip()
                end_time = (base + timedelta(days=diff_days, seconds=diff_seconds)).strftime(format_str).rstrip()

        return start_time, end_time, format_str, expected_format

    def score_answer(self, answer: Optional[str], entry: dict) -> float:
        """Score an answer based on how close it is to the expected duration

        Returns a score between 0 and 1, with partial credit for answers that are
        close to correct in the appropriate units/format
        """
        if not isinstance(answer, str):
            return 0.0

        expected = entry["answer"]
        task_type = entry["metadata"]["task_type"]

        try:
            if task_type == "date":
                # Parse "X days" format
                try:
                    actual = int(answer.strip().split()[0])  # Get number before "days"
                    expected = int(expected.strip().split()[0])
                    if actual == expected:
                        return 1.0
                    # Partial credit based on how close the day count is
                    max_diff = self.config.max_date_difference_days
                    diff = abs(actual - expected)
                    return max(0.0, 1.0 - (diff / max_diff))
                except (ValueError, IndexError):
                    return 0.0

            elif task_type.startswith("time"):
                # Parse times into total seconds for comparison
                def parse_time(t):
                    parts = t.strip().split(":")
                    seconds = int(parts[0]) * 3600 + int(parts[1]) * 60
                    if len(parts) > 2:
                        if "." in parts[2]:  # Has milliseconds
                            s, ms = parts[2].split(".")
                            seconds += int(s) + int(ms) / 1000
                        else:
                            seconds += int(parts[2])
                    return seconds

                actual_seconds = parse_time(answer)
                expected_seconds = parse_time(expected)

                if actual_seconds == expected_seconds:
                    return 1.0

                # Partial credit based on how close the times are
                max_diff = self.config.max_time_difference_seconds
                diff = abs(actual_seconds - expected_seconds)
                return max(0.0, 1.0 - (diff / max_diff))

            else:  # datetime or datetime_tz
                # Parse the complex format "X days, HH:MM" or "X days, HH:MM:SS"
                def parse_datetime(t):
                    days = int(t.split(" days,")[0])
                    time_part = t.split(",")[1].strip()
                    parts = time_part.split(":")
                    seconds = int(parts[0]) * 3600 + int(parts[1]) * 60
                    if len(parts) > 2:
                        seconds += int(parts[2])
                    return days * 86400 + seconds

                actual_seconds = parse_datetime(answer)
                expected_seconds = parse_datetime(expected)

                if actual_seconds == expected_seconds:
                    return 1.0

                # Partial credit based on total time difference
                max_diff = self.config.max_date_difference_days * 86400
                diff = abs(actual_seconds - expected_seconds)
                return max(0.0, 1.0 - (diff / max_diff))

        except (ValueError, IndexError):
            return 0.0  # Invalid format

        return 0.0


class TimeIntervalsCurriculum(BaseCurriculum):
    def __init__(self):
        super().__init__(TimeIntervalsCurriculum.__name__, TimeIntervalsConfig)

        # Define attributes
        self._define_attributes(
            ScalarAttributeDefinition(
                name="max_time_difference_seconds",
                field_name="max_time_difference_seconds",
                levels=[60, 24 * 60 * 60, 7 * 24 * 60 * 60, 30 * 24 * 60 * 60, 365 * 24 * 60 * 60],
                description="Maximum time difference in seconds",
            ),
            ScalarAttributeDefinition(
                name="max_date_difference_days",
                field_name="max_date_difference_days",
                levels=[1, 7, 30, 365, 5 * 365],
                description="Maximum date difference in days",
            ),
        )


# Register the dataset
register_dataset("time_intervals", TimeIntervalsDataset, TimeIntervalsConfig, TimeIntervalsCurriculum)