import { randomUUID } from 'node:crypto';
import type { CollectionDetail, CollectionMode, CollectionPreview, CollectionSummary } from '$lib/deployment-plan.js';
import { db } from '../db/index.js';
import { config, komodoConfigured, rconConfigured } from '../config.js';
import { blueprintEntries, summarizeRecipe, type BlueprintEntry } from './launch-recipes.js';
import { creationQueue, destroyServer, nextAvailablePort, nextLobbyNumber, queueCreateServer } from '../provisioning/index.js';
import { deploymentStage, finishDeployment, recordDeploymentEvent } from './deployments.js';
import { housePartyTargets } from './house-party.js';
import { getServerKey } from './server-keys.js';
import { classifyHealth } from './health.js';
import { getServer } from './servers.js';
import { parseServerName, zombieMapBySlug, zombieMaps } from './map-aliases.js';

function coverage(entries: BlueprintEntry[]) {
    type Server = { name: string; game: string | null; map_slug: string | null; map: string | null };
    const registered = db().prepare('SELECT name, game, map_slug, map FROM servers WHERE destroyed_at IS NULL').all() as Server[];
    const queued = db().prepare(`SELECT j.server AS name, substr(j.server, 1, 2) AS game, j.map_slug, j.expected_map AS map
        FROM server_creation_jobs j JOIN server_deployments d ON d.id = j.deployment_id
        WHERE d.state IN ('queued', 'running', 'awaiting-health')`).all() as Server[];
    const removing = new Set((db().prepare("SELECT server FROM server_deployments WHERE action = 'destroy' AND state IN ('waiting', 'running')").all() as { server: string }[]).map(row => row.server));
    // A provisioning server can appear in both tables; count its identity once.
    const servers = [...new Map([...queued, ...registered].map(server => [server.name, server])).values()];
    return entries.map(entry => {
        const existingServers = servers.filter(server => {
            if (removing.has(server.name)) return false;
            const parsed = parseServerName(server.name);
            const game = server.game ?? parsed?.game;
            if (game !== entry.recipe.game) return false;
            if (server.map_slug) return server.map_slug === entry.recipe.mapSlug;
            const namedMap = parsed?.mapCanonical ? zombieMapBySlug(game, parsed.mapSlug) : undefined;
            if (namedMap && (!server.map || server.map === namedMap.canonical)) return namedMap.slug === entry.recipe.mapSlug;
            // Legacy canonical maps are usable only when they identify one variant.
            const matches = zombieMaps(game).filter(map => map.canonical === server.map);
            return matches.length === 1 && matches[0].slug === entry.recipe.mapSlug;
        }).map(server => server.name).sort();
        const coverage = existingServers.map(name => {
            const operation = db().prepare("SELECT id, state FROM server_deployments WHERE server = ? AND action IN ('create','rebuild') AND state IN ('queued', 'running', 'awaiting-health') ORDER BY rowid DESC LIMIT 1").get(name) as { id: string; state: string } | undefined;
            const server = getServer(name);
            return { name, health: operation ? operation.state === 'queued' ? 'queued' : 'starting'
                : server?.container_state && !['running', 'starting', 'restarting'].includes(server.container_state) ? 'stopped'
                : classifyHealth(server?.last_seen_at ?? null, server?.last_error ?? null, server?.container_state),
                href: operation ? `/provisioning/${encodeURIComponent(operation.id)}` : `/servers/${encodeURIComponent(name)}` };
        });
        return { existingServers, coverage, existing: existingServers.length, missing: Math.max(0, entry.count - existingServers.length) };
    });
}

function fleetSnapshot() {
    return housePartyTargets().map(name => ({ name,
        server: db().prepare('SELECT game, map_slug, map, game_port FROM servers WHERE name = ?').get(name) ?? null,
        creation: db().prepare("SELECT id FROM server_deployments WHERE server = ? AND action IN ('create','rebuild') ORDER BY rowid DESC LIMIT 1").get(name) ?? null,
        removal: db().prepare("SELECT id FROM server_deployments WHERE server = ? AND action = 'destroy' AND state IN ('waiting', 'running')").get(name) ?? null
    }));
}

function collectionPlan(entries: BlueprintEntry[], mode: CollectionMode) {
    const counts = coverage(entries);
    // Preserve deployed lobbies before queued ones, then the lowest lobby IDs.
    const retainedServers = counts.flatMap((entry, index) => [...entry.existingServers].sort((a, b) =>
        Number(!!getServer(b)) - Number(!!getServer(a)) || a.localeCompare(b, 'en', { numeric: true })
    ).slice(0, mode === 'exact' ? entries[index].count : undefined));
    const retained = new Set(retainedServers);
    const matching = new Set(counts.flatMap(entry => entry.existingServers));
    const removals = mode === 'exact' ? housePartyTargets().filter(name => !retained.has(name)).map(name => ({ name,
        reason: matching.has(name) ? 'Exceeds the target lobby count' : 'Outside this collection or already awaiting removal'
    })) : [];
    return { counts, retainedServers, removals };
}

function allocate(entries: BlueprintEntry[], releasingServers: string[] = []): CollectionPreview['servers'] {
    const names: string[] = [];
    const ports: number[] = [];
    const counts = coverage(entries);
    return entries.flatMap((entry, entryIndex) => Array.from({ length: counts[entryIndex].missing }, () => {
        const base = `${entry.recipe.game}_zombie_${entry.recipe.mapSlug}`;
        const lobby = nextLobbyNumber(base, names);
        const name = lobby === null ? null : `${base}_${lobby}`;
        const port = nextAvailablePort(ports, releasingServers);
        if (name) names.push(name);
        if (port !== null) ports.push(port);
        return { entryIndex, name, port, hasSavedKey: !!name && !!getServerKey(name) };
    }));
}

function blockersFor(servers: CollectionPreview['servers']): string[] {
    const blockers: string[] = [];
    if (!servers.length) return blockers;
    if (!komodoConfigured() || !config.komodo.targetServer) blockers.push('Configure Komodo credentials and a target host before launching.');
    if (!rconConfigured()) blockers.push('Configure RCON_PASSWORD so every new server can be verified.');
    if (servers.some(server => !server.name)) blockers.push('There are not enough free lobbies for one or more maps (20 per map). Reduce their counts or free capacity.');
    if (servers.some(server => server.port === null)) blockers.push(`There are not enough free game ports in ${config.portRange.min}–${config.portRange.max} for the whole collection.`);
    return blockers;
}

export function previewCollection(blueprintId: unknown, mode: unknown = 'fill'): CollectionPreview {
    if (typeof blueprintId !== 'string' || !blueprintId) throw new Error('Choose a collection to launch.');
    if (mode !== 'fill' && mode !== 'exact') throw new Error('Choose fill or exact collection mode.');
    return db().transaction((): CollectionPreview => {
        const { entries, blueprintName } = blueprintEntries(blueprintId);
        const { counts, retainedServers, removals } = collectionPlan(entries, mode);
        const servers = allocate(entries, removals.map(server => server.name));
        const blockers = blockersFor(servers);
        if (removals.length && (!komodoConfigured() || !rconConfigured())) blockers.push('Configure Komodo and RCON before removing servers.');
        const id = randomUUID();
        const expiresAt = new Date(Date.now() + 30 * 60_000).toISOString();
        db().prepare('DELETE FROM server_collection_previews WHERE expires_at < ? AND collection_id IS NULL').run(new Date().toISOString());
        db().prepare('INSERT INTO server_collection_previews (id, expires_at, blueprint_name, entries, servers, mode, fleet_snapshot) VALUES (?, ?, ?, ?, ?, ?, ?)')
            .run(id, expiresAt, blueprintName, JSON.stringify(entries), JSON.stringify(servers), mode, mode === 'exact' ? JSON.stringify(fleetSnapshot()) : null);
        return { id, expiresAt, blueprintName, mode, retainedServers, removals, launchConcurrency: config.createConcurrency, servers, blockers, ready: blockers.length === 0,
            entries: entries.map((entry, index) => ({ count: entry.count, ...counts[index], recipe: summarizeRecipe(entry.recipe) })) };
    })();
}

/** Reserve and enqueue the entire collection atomically. No external operations here. */
export function queueCollection(input: { previewId?: unknown; keys?: unknown }): { ok: true; collectionId: string | null } {
    if (typeof input.previewId !== 'string' || !input.previewId) throw new Error('Review a collection preview before launching.');
    if (input.keys !== undefined && (!input.keys || typeof input.keys !== 'object' || Array.isArray(input.keys))) throw new Error('Provide keys indexed by the exact server ID.');
    const keys = (input.keys ?? {}) as Record<string, unknown>;
    return db().transaction(() => {
        const preview = db().prepare('SELECT * FROM server_collection_previews WHERE id = ?').get(input.previewId) as {
            id: string; expires_at: string; blueprint_name: string; entries: string; servers: string; collection_id: string | null; mode: CollectionMode; fleet_snapshot: string | null;
        } | undefined;
        if (!preview) throw new Error('Collection preview expired or was not found. Refresh the preview.');
        if (preview.collection_id) return { ok: true as const, collectionId: preview.collection_id };
        if (preview.expires_at <= new Date().toISOString()) throw new Error('Collection preview expired. Refresh it before launching.');
        const entries: BlueprintEntry[] = JSON.parse(preview.entries);
        const reviewed: CollectionPreview['servers'] = JSON.parse(preview.servers);
        if (preview.mode === 'exact' && preview.fleet_snapshot !== JSON.stringify(fleetSnapshot())) {
            throw new Error('The fleet changed. Nothing was queued. Refresh the preview and review the servers to keep and remove.');
        }
        const { retainedServers, removals } = collectionPlan(entries, preview.mode);
        const releasingServers = removals.map(server => server.name);
        const servers = allocate(entries, releasingServers);
        const blockers = blockersFor(servers);
        if (removals.length && (!komodoConfigured() || !rconConfigured())) blockers.push('Configure Komodo and RCON before removing servers.');
        if (blockers.length) throw new Error(blockers.join(' '));
        if (servers.length !== reviewed.length || servers.some((server, i) => server.entryIndex !== reviewed[i]?.entryIndex || server.name !== reviewed[i]?.name || server.port !== reviewed[i]?.port)) {
            throw new Error('Fleet counts, lobby or port availability changed. Nothing was queued. Refresh the preview and review each server key.');
        }
        const expected = new Set(servers.map(server => server.name));
        for (const [name, value] of Object.entries(keys)) {
            if (!expected.has(name) || typeof value !== 'string') throw new Error('Keys must be strings for server IDs shown in this preview.');
        }
        if (!servers.length && !removals.length) return { ok: true as const, collectionId: null };
        const collectionId = randomUUID();
        db().prepare('INSERT INTO server_launch_collections (id, name, created_at, mode, retained_servers) VALUES (?, ?, ?, ?, ?)')
            .run(collectionId, preview.blueprint_name, new Date().toISOString(), preview.mode, JSON.stringify(retainedServers));
        const removalJobs = removals.map((server, position) => {
            const ports = (db().prepare(`SELECT game_port AS port FROM servers WHERE name = ? UNION
                SELECT j.port FROM server_creation_jobs j JOIN server_deployments d ON d.id = j.deployment_id
                WHERE j.server = ? AND d.state IN ('queued', 'running', 'awaiting-health')`).all(server.name, server.name) as { port: number | null }[]).map(row => row.port);
            const queued = db().prepare("SELECT id FROM server_deployments WHERE server = ? AND action = 'create' AND state = 'queued'").get(server.name) as { id: string } | undefined;
            let id: string;
            if (queued && !getServer(server.name)) {
                // No container or files exist yet: cancel the reservation instead of booting just to remove it.
                const result = destroyServer(server.name, 'blueprint-exact');
                if (!result.ok || !result.deploymentId) throw new Error('Could not queue removal for ' + server.name);
                id = result.deploymentId;
                db().prepare("UPDATE server_deployments SET state = 'cancelled', stage = 'Cancelled by exact collection', finished_at = ? WHERE id = ?").run(new Date().toISOString(), queued.id);
                recordDeploymentEvent(queued.id, 'Queued creation cancelled by exact collection; saved key retained.');
                deploymentStage(id, 'Cancelled queued creation; no server was started');
                finishDeployment(id, { ok: true });
            } else {
                const result = destroyServer(server.name, 'blueprint-exact');
                if (!result.ok || !result.deploymentId) throw new Error('Could not queue removal for ' + server.name);
                id = result.deploymentId;
            }
            db().prepare('INSERT INTO server_collection_removals (collection_id, deployment_id, position) VALUES (?, ?, ?)').run(collectionId, id, position);
            return { id, ports };
        });
        servers.forEach((server, index) => {
            const recipe = entries[server.entryIndex].recipe;
            const childPreviewId = randomUUID();
            db().prepare('INSERT INTO server_launch_previews (id, expires_at, server, port, recipe, blueprint_name) VALUES (?, ?, ?, ?, ?, ?)')
                .run(childPreviewId, preview.expires_at, server.name, server.port, JSON.stringify(recipe), preview.blueprint_name);
            const result = queueCreateServer({ game: recipe.game, gameMode: 'zombie', mapSlug: recipe.mapSlug,
                expectedName: server.name!, previewId: childPreviewId, plutoKey: keys[server.name!] as string | undefined, createdBy: 'ui' }, releasingServers);
            // Throw so the outer transaction also reverses all earlier keys and children.
            if (!result.ok) throw new Error(`${server.name}: ${result.message} Nothing was queued.`);
            db().prepare('INSERT INTO server_collection_members (collection_id, deployment_id, position) VALUES (?, ?, ?)')
                .run(collectionId, result.deploymentId, index);
            for (const removal of removalJobs.filter(removal => removal.ports.includes(server.port))) {
                db().prepare('INSERT INTO server_creation_dependencies (deployment_id, removal_id) VALUES (?, ?)').run(result.deploymentId, removal.id);
            }
        });
        db().prepare('UPDATE server_collection_previews SET collection_id = ? WHERE id = ?').run(collectionId, preview.id);
        return { ok: true as const, collectionId };
    })();
}

const membershipSql = `SELECT collection_id, deployment_id, position FROM server_collection_members
    UNION ALL SELECT collection_id, deployment_id, position FROM server_collection_removals`;

const summarySql = `SELECT c.id, c.name, c.created_at, c.mode, COUNT(d.id) AS total,
    COALESCE(SUM(d.state IN ('done', 'warning')), 0) AS done,
    COALESCE(SUM(d.state IN ('failed', 'interrupted', 'cancelled')), 0) AS failed,
    COALESCE(SUM(d.state IN ('queued', 'running', 'awaiting-health', 'waiting')), 0) AS active,
    COALESCE(SUM(d.state IN ('queued', 'waiting')), 0) AS queued,
    COALESCE(SUM(d.state = 'running'), 0) AS provisioning,
    COALESCE(SUM(d.state = 'awaiting-health'), 0) AS verifying
    FROM server_launch_collections c
    LEFT JOIN (${membershipSql}) m ON m.collection_id = c.id
    LEFT JOIN server_deployments d ON d.id = m.deployment_id`;

export function listCollections(): CollectionSummary[] {
    return db().prepare(summarySql + ' GROUP BY c.id ORDER BY c.created_at DESC, c.rowid DESC').all() as CollectionSummary[];
}

export function getCollection(id: string): CollectionDetail | null {
    const collection = db().prepare(summarySql + ' WHERE c.id = ? GROUP BY c.id').get(id) as CollectionSummary | undefined;
    if (!collection) return null;
    const servers = db().prepare(`SELECT d.id, d.server, d.action, d.state, d.stage, d.started_at, d.finished_at, d.error, j.port, j.map_slug,
        EXISTS(SELECT 1 FROM servers s WHERE s.name = d.server) AS server_exists
        FROM (${membershipSql}) m JOIN server_deployments d ON d.id = m.deployment_id
        LEFT JOIN server_creation_jobs j ON j.deployment_id = d.id WHERE m.collection_id = ? ORDER BY d.action DESC, m.position`).all(id) as CollectionDetail['servers'];
    const queue = creationQueue();
    const positions = new Map(queue.queued.map((job, index) => [job.id, index + 1]));
    const stored = db().prepare('SELECT retained_servers FROM server_launch_collections WHERE id = ?').get(id) as { retained_servers: string };
    return { collection, retainedServers: JSON.parse(stored.retained_servers), queue: { concurrency: config.createConcurrency, active: queue.active, queued: queue.queued.length },
        servers: servers.map(server => ({ ...server, queuePosition: positions.get(server.id) ?? null })) };
}