import hashlib
from typing import Any
from ..config import get_settings
from ..models import PageContext, Channel
from ..schemas import NormalizedInboundEvent

def hash_sender(sender_id: str | None) -> str | None:
    return hashlib.sha256(sender_id.encode("utf-8")).hexdigest() if sender_id else None

def resolve_page_context(platform_page_id: str | None) -> PageContext:
    settings = get_settings()
    page_id = str(platform_page_id or "")
    for slug in settings.page_contexts():
        if page_id == settings.page_env(slug, "id"):
            return PageContext(slug)
    raise ValueError(f"Unrecognized platform_page_id: {platform_page_id}")

def normalize_meta_payload(payload: dict[str, Any]) -> list[NormalizedInboundEvent]:
    events: list[NormalizedInboundEvent] = []
    for entry in payload.get("entry", []) or []:
        page_id = str(entry.get("id", ""))
        page_context = resolve_page_context(page_id)
        for messaging in entry.get("messaging", []) or []:
            sender_id = messaging.get("sender", {}).get("id")
            recipient_id = messaging.get("recipient", {}).get("id")
            message = messaging.get("message") or {}
            postback = messaging.get("postback") or {}
            if message:
                events.append(NormalizedInboundEvent(page_context=page_context, platform_page_id=page_id or recipient_id, channel=Channel.messenger, event_type="message", sender_id_hash=hash_sender(sender_id), object_id=message.get("mid"), message_text=message.get("text"), normalized_payload={"sender_psid": sender_id, "recipient_id": recipient_id, "message": message}))
            if postback:
                events.append(NormalizedInboundEvent(page_context=page_context, platform_page_id=page_id or recipient_id, channel=Channel.messenger, event_type="postback", sender_id_hash=hash_sender(sender_id), object_id=postback.get("mid") or postback.get("payload"), message_text=postback.get("title"), normalized_payload={"sender_psid": sender_id, "recipient_id": recipient_id, "postback": postback}))
        for change in entry.get("changes", []) or []:
            field = change.get("field")
            value = change.get("value") or {}
            if field in {"feed", "comments", "mention"}:
                item = value.get("item")
                comment_id = value.get("comment_id")
                post_id = value.get("post_id")
                channel = Channel.comment if item == "comment" or comment_id else Channel.page_post
                verb = value.get("verb") or "change"
                events.append(NormalizedInboundEvent(page_context=page_context, platform_page_id=page_id, channel=channel, event_type=f"{field}:{verb}", sender_id_hash=hash_sender((value.get("from") or {}).get("id")), object_id=comment_id or post_id or value.get("id"), parent_id=post_id, message_text=value.get("message") or value.get("comment_message"), normalized_payload=value))
            if field == "leadgen":
                events.append(NormalizedInboundEvent(page_context=page_context, platform_page_id=page_id, channel=Channel.lead, event_type="leadgen", object_id=value.get("leadgen_id"), normalized_payload=value))
    return events