import logging
import time
from datetime import datetime

from yuxi.channel.cron.schedule import (
    compute_next_run_at_ms,
    is_recurring_top_of_hour_cron_expr,
    resolve_default_cron_stagger_ms,
)
from yuxi.channel.cron.types import (
    CronDeliveryTarget,
    CronFailureAlert,
    CronJob,
    ScheduleKind,
)

logger = logging.getLogger(__name__)

CRON_FIELD_COUNT = 5
CRON_FIELD_RANGES = [
    (0, 59),
    (0, 23),
    (1, 31),
    (1, 12),
    (0, 7),
]


def _validate_cron_expr_format(expr: str) -> str | None:
    parts = expr.strip().split()
    if len(parts) != CRON_FIELD_COUNT:
        return f"cron 表达式应包含 {CRON_FIELD_COUNT} 个字段，实际 {len(parts)} 个: {expr}"

    for i, (field, (lo, hi)) in enumerate(zip(parts, CRON_FIELD_RANGES)):
        for segment in field.split(","):
            step = 1
            if "/" in segment:
                segment, step_str = segment.split("/", 1)
                try:
                    step = int(step_str)
                except ValueError:
                    return f"cron 表达式字段 {i} 步长无效: {step_str}"
                if step < 1:
                    return f"cron 表达式字段 {i} 步长必须 >= 1: {step}"
            if segment == "*":
                continue
            if "-" in segment:
                try:
                    low_str, high_str = segment.split("-", 1)
                    low = int(low_str)
                    high = int(high_str)
                except ValueError:
                    return f"cron 表达式字段 {i} 范围格式无效: {segment}"
                if low < lo or high > hi or low > high:
                    return f"cron 表达式字段 {i} 范围 {low}-{high} 超出 [{lo}, {hi}]"
            else:
                try:
                    val = int(segment)
                except ValueError:
                    return f"cron 表达式字段 {i} 值无效: {segment}"
                if val < lo or val > hi:
                    return f"cron 表达式字段 {i} 值 {val} 超出 [{lo}, {hi}]"

    return None


def _validate_at_value(value: str) -> str | None:
    try:
        at_ms = int(value)
        if at_ms <= 0:
            return f"AT 调度值必须为正整数 (毫秒时间戳): {value}"
        return None
    except (ValueError, TypeError):
        pass
    try:
        datetime.fromisoformat(value)
        return None
    except (ValueError, TypeError):
        return f"AT 调度值格式无效 (需为毫秒时间戳或 ISO 8601): {value}"


def _validate_every_value(every_ms: int | None, anchor_ms: int | None) -> str | None:
    if every_ms is None:
        return "EVERY 调度必须设置 every_ms"
    if every_ms <= 0:
        return f"EVERY 调度的 every_ms 必须 > 0: {every_ms}"
    if anchor_ms is not None and anchor_ms < 0:
        return f"EVERY 调度的 anchor_ms 不能为负数: {anchor_ms}"
    return None


def _validate_delivery_target(target: CronDeliveryTarget) -> str | None:
    if not target.channel or not target.channel.strip():
        return f"投递目标缺少 channel: {target.to_dict()}"
    if not target.target_id or not target.target_id.strip():
        return f"投递目标缺少 target_id: {target.to_dict()}"
    return None


def normalize_job(job: CronJob) -> list[str]:
    warnings: list[str] = []

    if not job.id or not job.id.strip():
        warnings.append("CronJob.id 不能为空")
        job.id = job.id or f"unnamed_{int(time.time() * 1000)}"

    if not job.name:
        job.name = job.id
        warnings.append(f"未设置 name，已使用 id 作为名称: {job.name}")

    if job.error_threshold < 1:
        job.error_threshold = 5
        warnings.append(f"error_threshold 必须 >= 1，已重置为 {job.error_threshold}")

    if job.max_runs < 0:
        job.max_runs = 0
        warnings.append(f"max_runs 不能为负数，已重置为 0 (无限制)")

    if job.stagger_ms < 0:
        job.stagger_ms = 0
        warnings.append(f"stagger_ms 不能为负数，已重置为 0")

    if job.schedule_kind == ScheduleKind.CRON:
        err = _validate_cron_expr_format(job.schedule_value)
        if err:
            warnings.append(err)
        if job.stagger_ms == 0 and job.schedule_value:
            default_stagger = resolve_default_cron_stagger_ms(job.schedule_value)
            if default_stagger > 0:
                job.stagger_ms = default_stagger
                warnings.append(f"整点 CRON 表达式未设置 stagger，已自动设置 {default_stagger}ms 错峰")

    elif job.schedule_kind == ScheduleKind.AT:
        err = _validate_at_value(job.schedule_value)
        if err:
            warnings.append(err)
        if job.stagger_ms > 0:
            warnings.append("AT 调度不支持 stagger，已忽略")
            job.stagger_ms = 0

    elif job.schedule_kind == ScheduleKind.EVERY:
        err = _validate_every_value(job.every_ms, job.anchor_ms)
        if err:
            warnings.append(err)

    for i, target in enumerate(job.delivery):
        err = _validate_delivery_target(target)
        if err:
            warnings.append(f"投递目标 [{i}]: {err}")

    if job.failure_alert.threshold < 1:
        job.failure_alert.threshold = 5
        warnings.append(f"告警阈值必须 >= 1，已重置为 {job.failure_alert.threshold}")

    if job.failure_alert.cooldown_ms < 0:
        job.failure_alert.cooldown_ms = 600_000
        warnings.append(f"告警冷却时间不能为负数，已重置为 {job.failure_alert.cooldown_ms}ms")

    try:
        next_at = compute_next_run_at_ms(job)
        if next_at is not None:
            job.state.next_run_at_ms = next_at
    except Exception as e:
        warnings.append(f"无法计算下次执行时间: {e}")

    if warnings:
        logger.warning("CronJob '%s' 规范化产生 %d 条警告: %s", job.id, len(warnings), warnings)

    return warnings