use config::AppConfig;
use qdrant_client::qdrant::{
    CreateCollectionBuilder, CreateFieldIndexCollectionBuilder,
    DeletePointsBuilder, FieldType, PointStruct, QueryPointsBuilder,
    SearchParamsBuilder, UpsertPointsBuilder, VectorParamsBuilder,
};
use qdrant_client::{Qdrant, QdrantError};

use super::{
    config::RagConfig,
    document::{RagDocument, RagSearchHit},
    payload::{
        SESSION_ID_KEY, document_payload, hit_from_scored_point, point_id,
    },
    search::RagSearchOptions,
    session::{session_filter, validate_session_id},
};
use crate::{
    client::AiClient,
    embed::{AiClientEmbedExt, EmbedClient},
    error::{AiError, AiResult},
};

#[derive(Clone)]
pub struct RagClient {
    qdrant: Qdrant,
    embedder: EmbedClient,
    config: RagConfig,
}

impl RagClient {
    pub fn new(
        qdrant: Qdrant,
        embedder: EmbedClient,
        config: RagConfig,
    ) -> AiResult<Self> {
        config.validate()?;
        Ok(Self {
            qdrant,
            embedder,
            config,
        })
    }

    pub fn connect(
        ai_client: &AiClient,
        config: RagConfig,
    ) -> AiResult<Self> {
        config.validate()?;
        let mut builder =
            Qdrant::from_url(config.url.trim()).timeout(config.timeout);
        if let Some(api_key) = config
            .api_key
            .as_deref()
            .filter(|api_key| !api_key.trim().is_empty())
        {
            builder = builder.api_key(api_key);
        }

        Self::new(builder.build()?, ai_client.embedder()?, config)
    }

    pub fn from_app_config(
        ai_client: &AiClient,
        config: &AppConfig,
        collection_name: impl Into<String>,
    ) -> AiResult<Self> {
        Self::connect(
            ai_client,
            RagConfig::from_app_config(config, collection_name)?,
        )
    }

    pub fn qdrant(&self) -> &Qdrant {
        &self.qdrant
    }

    pub fn embedder(&self) -> &EmbedClient {
        &self.embedder
    }

    pub fn config(&self) -> &RagConfig {
        &self.config
    }

    pub async fn ensure_collection(&self) -> AiResult<()> {
        if !self
            .qdrant
            .collection_exists(&self.config.collection_name)
            .await?
        {
            self.qdrant
                .create_collection(
                    CreateCollectionBuilder::new(&self.config.collection_name)
                        .vectors_config(VectorParamsBuilder::new(
                            self.config.vector_size,
                            self.config.distance,
                        )),
                )
                .await?;
        }

        match self
            .qdrant
            .create_field_index(CreateFieldIndexCollectionBuilder::new(
                &self.config.collection_name,
                SESSION_ID_KEY,
                FieldType::Keyword,
            ))
            .await
        {
            Ok(_) => Ok(()),
            Err(QdrantError::ResponseError { .. }) => Ok(()),
            Err(error) => Err(error.into()),
        }
    }

    pub async fn upsert_document(
        &self,
        session_id: impl AsRef<str>,
        document: RagDocument,
    ) -> AiResult<()> {
        self.upsert_documents(session_id, vec![document]).await
    }

    pub async fn upsert_documents(
        &self,
        session_id: impl AsRef<str>,
        documents: Vec<RagDocument>,
    ) -> AiResult<()> {
        let session_id = session_id.as_ref();
        validate_session_id(session_id)?;
        validate_documents(&documents)?;

        let texts: Vec<String> = documents
            .iter()
            .map(|d| d.content.clone())
            .collect();
        let vectors = self
            .embedder
            .embed_texts_chunked(texts, self.config.upsert_batch_size)
            .await?;

        let points = documents
            .iter()
            .zip(vectors)
            .map(|(document, vector)| {
                Ok(PointStruct::new(
                    point_id(session_id, &document.id),
                    vector,
                    document_payload(session_id, document)?,
                ))
            })
            .collect::<AiResult<Vec<_>>>()?;

        self.qdrant
            .upsert_points(
                UpsertPointsBuilder::new(&self.config.collection_name, points)
                    .wait(true),
            )
            .await?;

        Ok(())
    }

    pub async fn search_session(
        &self,
        session_id: impl AsRef<str>,
        query: impl Into<String>,
    ) -> AiResult<Vec<RagSearchHit>> {
        let options = RagSearchOptions {
            limit: self.config.default_search_limit,
            exact: self.config.exact_session_search,
        };
        self.search_session_with_options(session_id, query, options)
            .await
    }

    pub async fn search_session_with_options(
        &self,
        session_id: impl AsRef<str>,
        query: impl Into<String>,
        options: RagSearchOptions,
    ) -> AiResult<Vec<RagSearchHit>> {
        let vector = self.embedder.embed_text(query.into()).await?;
        self.search_session_by_vector(session_id, vector, options)
            .await
    }

    pub async fn search_session_by_vector(
        &self,
        session_id: impl AsRef<str>,
        vector: Vec<f32>,
        options: RagSearchOptions,
    ) -> AiResult<Vec<RagSearchHit>> {
        let session_id = session_id.as_ref();
        validate_session_id(session_id)?;
        if options.limit == 0 {
            return Err(AiError::Config(
                "rag search limit must be greater than 0".to_string(),
            ));
        }

        let response = self
            .qdrant
            .query(
                QueryPointsBuilder::new(&self.config.collection_name)
                    .query(vector)
                    .limit(options.limit)
                    .filter(session_filter(session_id))
                    .with_payload(true)
                    .params(
                        SearchParamsBuilder::default().exact(options.exact),
                    ),
            )
            .await?;

        Ok(response
            .result
            .into_iter()
            .map(hit_from_scored_point)
            .collect())
    }

    pub async fn clear_session(
        &self,
        session_id: impl AsRef<str>,
    ) -> AiResult<()> {
        let session_id = session_id.as_ref();
        validate_session_id(session_id)?;

        self.qdrant
            .delete_points(
                DeletePointsBuilder::new(&self.config.collection_name)
                    .points(session_filter(session_id))
                    .wait(true),
            )
            .await?;

        Ok(())
    }
}

fn validate_documents(documents: &[RagDocument]) -> AiResult<()> {
    if documents.is_empty() {
        return Err(AiError::Config("rag documents are required".to_string()));
    }

    for document in documents {
        if document.id.trim().is_empty() {
            return Err(AiError::Config(
                "rag document id is required".to_string(),
            ));
        }
        if document.content.trim().is_empty() {
            return Err(AiError::Config(
                "rag document content is required".to_string(),
            ));
        }
    }

    Ok(())
}