from __future__ import annotations

from datetime import datetime
from typing import Any

from sqlalchemy import event
from sqlalchemy.orm import Session as OrmSession

from govoplan_core.core.change_sequence import record_change
from govoplan_core.core.sqlalchemy_change_tracking import (
    ensure_object_id,
    has_attr_changes,
    object_state,
    operation_for_object,
    previous_value,
)
from govoplan_campaign.backend.db.models import (
    Campaign,
    CampaignIssue,
    CampaignJob,
    CampaignShare,
    CampaignVersion,
    ImapAppendAttempt,
    SendAttempt,
    new_uuid,
)

CAMPAIGNS_MODULE_ID = "campaigns"
CAMPAIGNS_COLLECTION = "campaigns.campaigns"
CAMPAIGN_VERSIONS_COLLECTION = "campaigns.versions"
CAMPAIGN_JOBS_COLLECTION = "campaigns.jobs"
CAMPAIGN_ISSUES_COLLECTION = "campaigns.issues"
CAMPAIGN_ATTEMPTS_COLLECTION = "campaigns.attempts"

_REGISTERED = False


def register_campaign_change_tracking() -> None:
    global _REGISTERED
    if _REGISTERED:
        return
    event.listen(OrmSession, "before_flush", _record_campaign_changes)
    _REGISTERED = True


def _record_campaign_changes(session: OrmSession, _flush_context: object, _instances: object) -> None:
    for obj in tuple(session.new) + tuple(session.dirty) + tuple(session.deleted):
        if isinstance(obj, Campaign):
            _record_campaign_change(session, obj)
        elif isinstance(obj, CampaignShare):
            _record_share_visibility_change(session, obj)
        elif isinstance(obj, CampaignVersion):
            _record_version_change(session, obj)
        elif isinstance(obj, CampaignJob):
            _record_job_change(session, obj)
        elif isinstance(obj, CampaignIssue):
            _record_issue_change(session, obj)
        elif isinstance(obj, (SendAttempt, ImapAppendAttempt)):
            _record_attempt_change(session, obj)


def _record_campaign_change(session: OrmSession, campaign: Campaign) -> None:
    operation = _operation_for_campaign(
        campaign,
        changed_attrs=(
            "external_id",
            "name",
            "description",
            "status",
            "current_version_id",
            "owner_user_id",
            "owner_group_id",
            "settings",
            "mail_profile_policy",
        ),
    )
    if operation is None:
        return
    campaign_id = _ensure_id(campaign)
    record_change(
        session,
        module_id=CAMPAIGNS_MODULE_ID,
        collection=CAMPAIGNS_COLLECTION,
        resource_type="campaign",
        resource_id=campaign_id,
        operation=operation,
        tenant_id=campaign.tenant_id,
        actor_type="user" if campaign.created_by_user_id else None,
        actor_id=campaign.created_by_user_id,
        payload=_campaign_payload(campaign),
    )


def _record_share_visibility_change(session: OrmSession, share: CampaignShare) -> None:
    state = object_state(share)
    if not share.campaign_id:
        return
    if not state.deleted and not state.pending and not has_attr_changes(
        state,
        ("campaign_id", "target_type", "target_id", "permission", "revoked_at"),
    ):
        return
    _ensure_id(share)
    operation = "deleted" if state.deleted or share.revoked_at is not None else "updated"
    campaign = session.get(Campaign, share.campaign_id)
    payload = _campaign_payload(campaign) if campaign is not None else {"campaign_id": share.campaign_id}
    payload.update({
        "share_id": share.id,
        "share_target_type": share.target_type,
        "share_target_id": share.target_id,
        "share_permission": share.permission,
        "share_revoked_at": _isoformat(share.revoked_at),
    })
    record_change(
        session,
        module_id=CAMPAIGNS_MODULE_ID,
        collection=CAMPAIGNS_COLLECTION,
        resource_type="campaign",
        resource_id=share.campaign_id,
        operation=operation,
        tenant_id=share.tenant_id,
        actor_type="user" if share.created_by_user_id else None,
        actor_id=share.created_by_user_id,
        payload=payload,
    )


def _record_version_change(session: OrmSession, version: CampaignVersion) -> None:
    operation = _operation_for_object(
        version,
        changed_attrs=(
            "raw_json",
            "schema_version",
            "source_filename",
            "source_base_path",
            "workflow_state",
            "current_flow",
            "current_step",
            "is_complete",
            "editor_state",
            "autosaved_at",
            "published_at",
            "locked_at",
            "locked_by_user_id",
            "user_lock_state",
            "user_locked_at",
            "user_locked_by_user_id",
            "validation_summary",
            "build_summary",
            "execution_snapshot_hash",
            "execution_snapshot_at",
        ),
    )
    if operation is None:
        return
    version_id = _ensure_id(version)
    campaign = session.get(Campaign, version.campaign_id) if version.campaign_id else None
    record_change(
        session,
        module_id=CAMPAIGNS_MODULE_ID,
        collection=CAMPAIGN_VERSIONS_COLLECTION,
        resource_type="campaign_version",
        resource_id=version_id,
        operation=operation,
        tenant_id=campaign.tenant_id if campaign is not None else None,
        payload={
            **(_campaign_payload(campaign) if campaign is not None else {"campaign_id": version.campaign_id}),
            "version_id": version_id,
            "version_number": version.version_number,
            "workflow_state": version.workflow_state,
            "current_flow": version.current_flow,
            "current_step": version.current_step,
        },
    )


def _record_job_change(session: OrmSession, job: CampaignJob) -> None:
    operation = _operation_for_object(
        job,
        changed_attrs=(
            "build_status",
            "validation_status",
            "queue_status",
            "send_status",
            "imap_status",
            "attempt_count",
            "last_error",
            "queued_at",
            "claimed_at",
            "smtp_started_at",
            "outcome_unknown_at",
            "sent_at",
            "resolved_recipients",
            "resolved_attachments",
            "issues_snapshot",
        ),
    )
    if operation is None:
        return
    job_id = _ensure_id(job)
    campaign = session.get(Campaign, job.campaign_id) if job.campaign_id else None
    record_change(
        session,
        module_id=CAMPAIGNS_MODULE_ID,
        collection=CAMPAIGN_JOBS_COLLECTION,
        resource_type="campaign_job",
        resource_id=job_id,
        operation=operation,
        tenant_id=job.tenant_id,
        payload={
            **(_campaign_payload(campaign) if campaign is not None else {"campaign_id": job.campaign_id}),
            "job_id": job_id,
            "version_id": job.campaign_version_id,
            "entry_index": job.entry_index,
            "entry_id": job.entry_id,
            "build_status": job.build_status,
            "validation_status": job.validation_status,
            "queue_status": job.queue_status,
            "send_status": job.send_status,
            "imap_status": job.imap_status,
        },
    )


def _record_issue_change(session: OrmSession, issue: CampaignIssue) -> None:
    operation = _operation_for_object(issue, changed_attrs=("severity", "code", "message", "source", "behavior"))
    if operation is None:
        return
    issue_id = _ensure_id(issue)
    campaign = session.get(Campaign, issue.campaign_id) if issue.campaign_id else None
    record_change(
        session,
        module_id=CAMPAIGNS_MODULE_ID,
        collection=CAMPAIGN_ISSUES_COLLECTION,
        resource_type="campaign_issue",
        resource_id=issue_id,
        operation=operation,
        tenant_id=issue.tenant_id,
        payload={
            **(_campaign_payload(campaign) if campaign is not None else {"campaign_id": issue.campaign_id}),
            "issue_id": issue_id,
            "version_id": issue.campaign_version_id,
            "job_id": issue.job_id,
            "severity": issue.severity,
            "code": issue.code,
        },
    )


def _record_attempt_change(session: OrmSession, attempt: SendAttempt | ImapAppendAttempt) -> None:
    operation = _operation_for_object(
        attempt,
        changed_attrs=("status", "claim_token", "smtp_status_code", "smtp_response", "error_type", "error_message", "folder"),
    )
    if operation is None:
        return
    attempt_id = _ensure_id(attempt)
    job = session.get(CampaignJob, attempt.job_id) if attempt.job_id else None
    if job is None:
        return
    campaign = session.get(Campaign, job.campaign_id) if job.campaign_id else None
    record_change(
        session,
        module_id=CAMPAIGNS_MODULE_ID,
        collection=CAMPAIGN_ATTEMPTS_COLLECTION,
        resource_type="campaign_attempt",
        resource_id=attempt_id,
        operation=operation,
        tenant_id=job.tenant_id,
        payload={
            **(_campaign_payload(campaign) if campaign is not None else {"campaign_id": job.campaign_id}),
            "attempt_id": attempt_id,
            "attempt_kind": "imap" if isinstance(attempt, ImapAppendAttempt) else "smtp",
            "job_id": job.id,
            "version_id": job.campaign_version_id,
        },
    )


def _operation_for_campaign(obj: Campaign, *, changed_attrs: tuple[str, ...]) -> str | None:
    state = object_state(obj)
    if state.pending:
        return "created"
    if state.deleted:
        return "deleted"
    if not has_attr_changes(state, changed_attrs):
        return None
    status_history = state.attrs.status.history
    if status_history.has_changes() and any(value == "deleted" for value in status_history.added):
        return "deleted"
    return "updated"


def _operation_for_object(obj: object, *, changed_attrs: tuple[str, ...]) -> str | None:
    return operation_for_object(obj, changed_attrs=changed_attrs)


def _ensure_id(obj: object) -> str:
    return ensure_object_id(obj, new_uuid)


def _campaign_payload(campaign: Campaign | None) -> dict[str, Any]:
    if campaign is None:
        return {}
    return {
        "campaign_id": campaign.id,
        "owner_user_id": campaign.owner_user_id,
        "owner_group_id": campaign.owner_group_id,
        "previous_owner_user_id": previous_value(campaign, "owner_user_id"),
        "previous_owner_group_id": previous_value(campaign, "owner_group_id"),
        "status": campaign.status,
        "previous_status": previous_value(campaign, "status"),
        "current_version_id": campaign.current_version_id,
        "previous_current_version_id": previous_value(campaign, "current_version_id"),
    }


def _isoformat(value: datetime | None) -> str | None:
    return value.isoformat() if value else None


__all__ = [
    "CAMPAIGNS_COLLECTION",
    "CAMPAIGNS_MODULE_ID",
    "CAMPAIGN_ATTEMPTS_COLLECTION",
    "CAMPAIGN_ISSUES_COLLECTION",
    "CAMPAIGN_JOBS_COLLECTION",
    "CAMPAIGN_VERSIONS_COLLECTION",
    "register_campaign_change_tracking",
]