import json
import secrets

from django.contrib import messages
from django.contrib.auth.decorators import login_required
from django.shortcuts import get_object_or_404, redirect, render
from django.http import JsonResponse
from django.urls import reverse
from django.utils import timezone
from django.utils.safestring import mark_safe
from django.views.decorators.http import require_GET, require_http_methods, require_POST

from messaging.services import parse_scheduled_for
from social.crypto import encrypt_tokens
from social.models import (
    Platform,
    SocialAccount,
    SocialAppCredentials,
    SocialPost,
    SocialPostTarget,
)
from social.oauth_linkedin import (
    LinkedInOAuthError,
    authorization_url,
    credentials_configured,
    exchange_code,
    fetch_member_profile,
    get_app_credentials,
    redirect_uri as linkedin_redirect_uri,
    token_blob_from_oauth,
)
from social.ollama import OllamaError, generate_social_post
from social.tasks import publish_social_post

CONNECT_INSTRUCTIONS = {
    Platform.FACEBOOK: {
        "title": "Connect Facebook Page",
        "steps": [
            mark_safe(
                'Go to <a href="https://developers.facebook.com/async/registration" '
                'target="_blank" rel="noopener">Meta developer registration</a> '
                "(opens in a new tab) and fill out the information."
            ),
            "Open Meta for Developers → your app → Tools → Graph API Explorer.",
            "Select your app, then Get Page Access Token for the Page you manage.",
            "Grant pages_manage_posts and pages_read_engagement (and pages_show_list).",
            "Copy the Page access token and the numeric Page ID.",
            "Paste both below. Tokens are encrypted at rest.",
        ],
        "docs_url": "https://developers.facebook.com/docs/pages/access-tokens/",
        "fields": [
            ("label", "Display name", "Monica Dhillon · EXIT"),
            ("external_id", "Page ID", "1029384756"),
            ("access_token", "Page access token", ""),
        ],
    },
    Platform.INSTAGRAM: {
        "title": "Connect Instagram Business",
        "steps": [
            "Instagram publishing uses a Facebook Page linked to an IG professional account.",
            "In Meta Business Suite, confirm the IG account is connected to your Page.",
            "From Graph API Explorer, get a Page token that can manage the linked IG account.",
            "Use the Instagram Business Account ID (not the username) as External ID.",
            "Paste Page access token + IG business account ID below.",
        ],
        "docs_url": "https://developers.facebook.com/docs/instagram-api/getting-started/",
        "fields": [
            ("label", "Display name", "@mkdrealtor"),
            ("external_id", "IG business account ID", ""),
            ("access_token", "Page access token", ""),
            ("page_id", "Facebook Page ID (optional)", ""),
        ],
    },
    Platform.LINKEDIN: {
        "title": "Connect LinkedIn",
        "oauth": True,
        "steps": [
            mark_safe(
                'Create a LinkedIn app in the '
                '<a href="https://www.linkedin.com/developers/apps" target="_blank" '
                'rel="noopener">LinkedIn Developer Portal</a>.'
            ),
            "Products tab — request “Sign In with LinkedIn using OpenID Connect” "
            "and “Share on LinkedIn”.",
            "Auth tab — under Authorized redirect URLs, paste the callback URL "
            "shown in the box below (exact match required).",
            "Auth tab — copy Client ID and Primary Client Secret into the fields below, "
            "then Save app credentials.",
            "Click Connect with LinkedIn to authorize. Access tokens last ~2 months; "
            "use Re-authorize when publishing fails with auth errors.",
        ],
        "docs_url": "https://learn.microsoft.com/en-us/linkedin/shared/authentication/authorization-code-flow",
        "fields": [],
    },
}


@login_required
def post_list(request):
    posts = SocialPost.objects.all()[:100]
    return render(request, "social/post_list.html", {"posts": posts})


@login_required
def post_detail(request, pk):
    post = get_object_or_404(SocialPost.objects.prefetch_related("targets"), pk=pk)
    return render(request, "social/post_detail.html", {"post": post})


@login_required
@require_http_methods(["GET", "POST"])
def account_list(request):
    accounts = SocialAccount.objects.all()
    connect_platform = (request.GET.get("connect") or "").strip()
    if connect_platform not in Platform.values:
        connect_platform = ""

    if request.method == "POST":
        action = (request.POST.get("action") or "connect").strip()
        if action == "disconnect":
            pk = request.POST.get("account_id")
            account = get_object_or_404(SocialAccount, pk=pk)
            account.is_active = False
            account.encrypted_tokens = ""
            account.save(update_fields=["is_active", "encrypted_tokens", "updated_at"])
            messages.success(request, f"Disconnected {account.label}.")
            return redirect("social:account_list")
        if action == "reactivate":
            pk = request.POST.get("account_id")
            account = get_object_or_404(SocialAccount, pk=pk)
            account.is_active = True
            account.save(update_fields=["is_active", "updated_at"])
            messages.success(request, f"Reactivated {account.label}.")
            return redirect("social:account_list")
        if action == "save_linkedin_app":
            client_id = (request.POST.get("client_id") or "").strip()
            client_secret = (request.POST.get("client_secret") or "").strip()
            if not client_id:
                messages.error(request, "Client ID is required.")
                return redirect(f"{request.path}?connect=linkedin")
            app, _created = SocialAppCredentials.objects.get_or_create(
                platform=Platform.LINKEDIN
            )
            app.client_id = client_id
            if client_secret:
                app.encrypted_client_secret = encrypt_tokens(client_secret)
            elif not app.encrypted_client_secret:
                messages.error(
                    request,
                    "Client Secret is required the first time you save LinkedIn app credentials.",
                )
                return redirect(f"{request.path}?connect=linkedin")
            app.save()
            messages.success(
                request,
                "LinkedIn app credentials saved. You can Connect with LinkedIn now.",
            )
            return redirect(f"{request.path}?connect=linkedin")

        platform = (request.POST.get("platform") or "").strip()
        if platform not in Platform.values:
            messages.error(request, "Choose a platform.")
            return redirect("social:account_list")
        label = (request.POST.get("label") or "").strip() or platform.title()
        external_id = (request.POST.get("external_id") or "").strip()
        access_token = (request.POST.get("access_token") or "").strip()
        page_id = (request.POST.get("page_id") or "").strip()
        if not access_token or not external_id:
            messages.error(request, "Access token and external ID are required.")
            return redirect(f"{request.path}?connect={platform}")

        token_blob = {"access_token": access_token}
        if platform == Platform.FACEBOOK:
            token_blob["page_id"] = external_id
        elif platform == Platform.INSTAGRAM:
            if page_id:
                token_blob["page_id"] = page_id
        elif platform == Platform.LINKEDIN:
            token_blob["author_urn"] = external_id

        account, created = SocialAccount.objects.update_or_create(
            platform=platform,
            external_id=external_id,
            defaults={
                "label": label,
                "encrypted_tokens": encrypt_tokens(json.dumps(token_blob)),
                "is_active": True,
                "owner": request.user,
            },
        )
        verb = "Connected" if created else "Updated"
        messages.success(request, f"{verb} {account.get_platform_display()} · {account.label}.")
        return redirect("social:account_list")

    linkedin_app = get_app_credentials()
    linkedin_oauth_ready = credentials_configured()
    linkedin_callback = ""
    try:
        linkedin_callback = linkedin_redirect_uri()
    except LinkedInOAuthError:
        linkedin_callback = "(set PUBLIC_SITE_URL, then restart)"

    return render(
        request,
        "social/account_list.html",
        {
            "accounts": accounts,
            "connect_platform": connect_platform,
            "connect_meta": CONNECT_INSTRUCTIONS.get(connect_platform),
            "platforms": Platform,
            "linkedin_oauth_ready": linkedin_oauth_ready,
            "linkedin_callback_url": linkedin_callback,
            "linkedin_client_id": (linkedin_app.client_id if linkedin_app else ""),
            "linkedin_secret_saved": bool(
                linkedin_app and linkedin_app.encrypted_client_secret
            ),
        },
    )


@login_required
@require_GET
def linkedin_oauth_start(request):
    """Redirect browser to LinkedIn consent screen."""
    if not credentials_configured():
        messages.error(
            request,
            "Save LinkedIn Client ID and Client Secret on the Connect LinkedIn form first.",
        )
        return redirect(f"{reverse('social:account_list')}?connect=linkedin")
    state = secrets.token_urlsafe(24)
    request.session["linkedin_oauth_state"] = state
    try:
        return redirect(authorization_url(state=state))
    except LinkedInOAuthError as exc:
        messages.error(request, str(exc))
        return redirect(f"{reverse('social:account_list')}?connect=linkedin")


@login_required
@require_GET
def linkedin_oauth_callback(request):
    """Handle LinkedIn redirect: exchange code, store encrypted SocialAccount."""
    error = (request.GET.get("error") or "").strip()
    if error:
        desc = (request.GET.get("error_description") or error).strip()
        messages.error(request, f"LinkedIn authorization denied: {desc}")
        return redirect("social:account_list")

    state = (request.GET.get("state") or "").strip()
    expected = request.session.pop("linkedin_oauth_state", None)
    if not state or not expected or state != expected:
        messages.error(request, "LinkedIn OAuth state mismatch — try Connect again.")
        return redirect("social:account_list")

    code = (request.GET.get("code") or "").strip()
    if not code:
        messages.error(request, "LinkedIn did not return an authorization code.")
        return redirect("social:account_list")

    try:
        token_payload = exchange_code(code)
        profile = fetch_member_profile(token_payload["access_token"])
        author_urn = profile["author_urn"]
        blob = token_blob_from_oauth(token_payload, author_urn=author_urn)
        account, created = SocialAccount.objects.update_or_create(
            platform=Platform.LINKEDIN,
            external_id=author_urn,
            defaults={
                "label": profile["label"],
                "encrypted_tokens": encrypt_tokens(json.dumps(blob)),
                "is_active": True,
                "owner": request.user,
            },
        )
    except LinkedInOAuthError as exc:
        messages.error(request, str(exc))
        return redirect("social:account_list")
    except Exception:
        messages.error(
            request,
            "Unexpected error saving LinkedIn account. Check app logs.",
        )
        raise

    verb = "Connected" if created else "Re-authorized"
    messages.success(
        request,
        f"{verb} LinkedIn · {account.label}. You can post from the composer.",
    )
    return redirect("social:account_list")


@login_required
@require_http_methods(["GET", "POST"])
def composer(request):
    """Compose, schedule, or publish to connected social accounts."""
    accounts = list(SocialAccount.objects.filter(is_active=True))
    form = {
        "body": "",
        "prompt": "",
        "publish_mode": "schedule",
        "scheduled_for": "",
        "account_ids": [],
    }
    error = ""
    draft = ""

    if request.method == "POST":
        form["body"] = (request.POST.get("body") or "").strip()
        form["prompt"] = (request.POST.get("prompt") or "").strip()
        form["publish_mode"] = (request.POST.get("publish_mode") or "schedule").strip()
        form["scheduled_for"] = request.POST.get("scheduled_for") or ""
        form["account_ids"] = request.POST.getlist("account_ids")
        action = (request.POST.get("action") or "save").strip()

        if action == "generate" and form["prompt"]:
            try:
                draft = generate_social_post(form["prompt"])
                form["body"] = draft
            except OllamaError as exc:
                error = str(exc)
        elif action in {"save", "publish"}:
            if not form["body"]:
                error = "Caption / body is required."
            elif form["publish_mode"] != "draft" and not form["account_ids"]:
                error = "Select at least one connected account."
            else:
                scheduled_for = None
                status = SocialPost.Status.DRAFT
                if form["publish_mode"] == "draft":
                    status = SocialPost.Status.DRAFT
                elif form["publish_mode"] == "schedule":
                    try:
                        scheduled_for = parse_scheduled_for(form["scheduled_for"])
                    except ValueError as exc:
                        error = str(exc)
                    else:
                        if not scheduled_for:
                            error = "Pick a schedule date/time, or choose Publish now."
                        else:
                            status = SocialPost.Status.SCHEDULED
                elif form["publish_mode"] == "now":
                    status = SocialPost.Status.QUEUED
                    scheduled_for = timezone.now()
                else:
                    error = "Unknown publish mode."

                if not error:
                    selected = SocialAccount.objects.filter(
                        pk__in=form["account_ids"], is_active=True
                    )
                    if form["publish_mode"] != "draft" and not selected.exists():
                        error = "No valid accounts selected."
                    else:
                        post = SocialPost.objects.create(
                            body=form["body"],
                            ollama_prompt=form["prompt"],
                            scheduled_for=scheduled_for,
                            status=status,
                            created_by=request.user,
                        )
                        for account in selected:
                            SocialPostTarget.objects.create(
                                post=post,
                                account=account,
                                platform=account.platform,
                            )
                        if status == SocialPost.Status.QUEUED:
                            publish_social_post.enqueue(post_id=str(post.pk))
                            messages.success(
                                request,
                                "Post queued for publishing to selected accounts.",
                            )
                        elif status == SocialPost.Status.SCHEDULED:
                            messages.success(
                                request,
                                f"Post scheduled for {scheduled_for:%b %d, %I:%M %p}.",
                            )
                        else:
                            messages.success(request, "Draft saved.")
                        return redirect("social:post_detail", pk=post.pk)

    return render(
        request,
        "social/composer.html",
        {
            "accounts": accounts,
            "form": form,
            "error": error,
            "draft": draft or form["body"],
        },
    )


@login_required
@require_POST
def api_generate(request):
    """
    JSON endpoint for the portal to draft posts via Ollama.

    POST JSON: {"prompt": "...", "platform": "facebook"|...}
    """
    try:
        payload = json.loads(request.body.decode() or "{}")
    except json.JSONDecodeError:
        payload = request.POST.dict()
    prompt = (payload.get("prompt") or "").strip()
    if not prompt:
        return JsonResponse({"error": "prompt required"}, status=400)
    try:
        text = generate_social_post(
            prompt, platform=(payload.get("platform") or "").strip()
        )
    except OllamaError as exc:
        return JsonResponse({"error": str(exc)}, status=502)
    return JsonResponse({"text": text})