import { ref } from 'vue'
import type { Agent } from '~~/types'

export const useAgents = async () => {
    const { addTask, completeTask } = useTasks()
    const appState = useAppState()

    const fetchingAgents = ref(false);
    const agents: Ref<Agent[] | null> = useState('agents', () => null);
    
    const activeAgent = computed(() => {
        if (agents.value === null) return;
        if (!appState.activeAgentId.value) return;

        const agent = agents.value.find(agent => agent.id === appState.activeAgentId.value);
        return agent;
    });

    const refreshAgents = async () => {
        if (fetchingAgents.value) return;
        fetchingAgents.value = true;

        const { data, error } = await useFetch('/api/agents');
        if (error.value) throw error;
        agents.value = data.value!;

        fetchingAgents.value = false;
    }

    if (agents.value === null) await refreshAgents();

    const createAgent = async () => {
        const taskHandle = addTask()

        try {
            const agent = await $fetch('/api/agents', {
                method: 'POST',
                headers: {
                    'Content-Type': 'application/json'
                },
                body: JSON.stringify({
                    name: 'New Agent',
                    systemPrompt: 'You are a helpful assistant.'
                })
            });

            if (agent === undefined) throw new Error('Failed to create agent');

            if (agents.value === null) agents.value = [];

            agents.value.push(agent);

            completeTask(taskHandle)

            return agent;
        } catch (error) {
            console.error(error);
            completeTask(taskHandle)
            return;
        }
    }

    let debounceTimeout: NodeJS.Timeout | null = null;
    const updateAgent = async (id: string, data: Partial<Agent>) => {
        if (agents.value === null) agents.value = [];

        // update the local state always
        agents.value = agents.value.map(agent => {
            if (agent.id === id) return { ...agent, ...data };
            return agent;
        });

        // falling edge debounce (when the user stops typing)
        if (debounceTimeout !== null) clearTimeout(debounceTimeout);
        debounceTimeout = setTimeout(async () => {
            const taskHandle = addTask()

            try {
                const agent = await $fetch(`/api/agents/${id}`, {
                    method: 'PATCH',
                    headers: {
                        'Content-Type': 'application/json'
                    },
                    body: JSON.stringify(data)
                });

                if (agent === undefined) throw new Error('Failed to update agent');

                const index = agents.value!.findIndex(agent => agent.id === id);
                if (index === -1) throw new Error('Agent not found');
                if (agents.value![index] === null) throw new Error('Agent not found');

                agents.value![index] = agent;

                completeTask(taskHandle)

                return agent;
            } catch (error) {
                console.error(error);
                completeTask(taskHandle)
                return;
            }
        }, 500);
    }

    return { agents, createAgent, activeAgent, updateAgent };
}