use std::sync::Arc;

use futures::{Stream, StreamExt as _, TryStreamExt as _};
pub use lb_chain_broadcast_service::BlockInfo;
pub use lb_chain_service::{ChainServiceInfo, CryptarchiaInfo, PhaseTag, Slot, State};
pub use lb_core::events::{Event, Events, TxEventPayload};
use lb_core::{
    block::MAX_BLOCK_TRANSACTIONS_SIZE,
    header::{ContentId, HeaderId},
    mantle::{
        SignedMantleTx, channel::ChannelState, ops::channel::ChannelId,
        transactions::states::Unverified,
    },
    proofs::leader_proof::Groth16LeaderProof,
    sdp::{DeclarationId, DeclarationMessage},
};
use lb_groth16::fr_to_bytes;
pub use lb_http_api_common::TimeInfo;
use lb_http_api_common::{
    MAX_BLOCKS_STREAM_BLOCKS, MAX_BLOCKS_STREAM_CHUNK_SIZE,
    bodies::{
        blend::JoinBlendRequestBody,
        mantle::GasPricesResponseBody,
        wallet::{
            balance::WalletBalanceResponseBody,
            claimable_vouchers::WalletClaimableVouchersResponseBody,
            fund::{WalletFundRequestBody, WalletFundResponseBody},
            transfer_funds::{WalletTransferFundsRequestBody, WalletTransferFundsResponseBody},
        },
    },
    paths::{
        BLEND_DISPERSE_TRANSACTION, BLEND_JOIN_NETWORK, BLEND_PENDING_TRANSACTIONS, BLOCK_EVENTS,
        BLOCKS, BLOCKS_DETAIL, BLOCKS_RANGE_STREAM, BLOCKS_STREAM, CHANNEL, CRYPTARCHIA_INFO,
        CRYPTARCHIA_LIB_STREAM, LEADER_CLAIM_VOUCHERS, MANTLE_GAS_PRICES, MEMPOOL_ADD_TX,
        NODE_VERSION, SDP_POST_DECLARATION, TIME_INFO,
        wallet::{BALANCE, FUND, TRANSACTIONS_TRANSFER_FUNDS},
    },
    queries::BlocksStreamQuery,
    settings::default_max_body_size,
};
use lb_key_management_system_keys::keys::{Ed25519Signature, ZkPublicKey};
use lb_log_targets::http_client;
use log::warn;
use reqwest::{Client, ClientBuilder, RequestBuilder, StatusCode, Url};
use serde::{Deserialize, Serialize, de::DeserializeOwned};
use tokio_util::{
    codec::{FramedRead, LinesCodec},
    io::StreamReader,
};

const LOG_TARGET: &str = http_client::ROOT;

/// Client-side header representation matching the server's
/// `ApiHeaderSerializer`.
#[derive(Clone, Debug, Deserialize)]
pub struct ApiHeader {
    pub id: HeaderId,
    pub parent_block: HeaderId,
    pub slot: Slot,
    pub body_root: ContentId,
    pub proof_of_leadership: Groth16LeaderProof,
}

/// Client-side block representation matching the server's `ApiBlockSerializer`.
/// Note: The server omits the signature field.
#[derive(Clone, Debug, Deserialize)]
pub struct ApiBlock {
    pub header: ApiHeader,
    pub uncle_headers: Vec<ApiSignedHeader>,
    pub transactions: Vec<SignedMantleTx<Unverified>>,
}

/// Client-side signed header representation matching the server's
/// `ApiSignedHeader`.
#[derive(Clone, Debug, Deserialize)]
pub struct ApiSignedHeader {
    pub header: ApiHeader,
    pub signature: Ed25519Signature,
}

/// Processed block event from the block stream.
/// Matches the server's `ApiProcessedBlockEvent`.
#[derive(Clone, Debug, Deserialize)]
pub struct ProcessedBlockEvent {
    pub block: ApiBlock,
    pub tip: HeaderId,
    pub tip_slot: Slot,
    pub lib: HeaderId,
    pub lib_slot: Slot,
}

#[derive(thiserror::Error, Debug)]
pub enum Error {
    #[error("Internal server error: {0}")]
    Server(String),
    #[error("Failed to execute request: {0}")]
    Client(String),
    #[error(transparent)]
    Request(#[from] reqwest::Error),
    #[error(transparent)]
    Url(#[from] url::ParseError),
}

#[derive(Clone)]
pub struct BasicAuthCredentials {
    username: String,
    password: Option<String>,
}

impl BasicAuthCredentials {
    #[must_use]
    pub const fn new(username: String, password: Option<String>) -> Self {
        Self { username, password }
    }
}

#[derive(Clone)]
pub struct CommonHttpClient {
    client: Arc<Client>,
    basic_auth: Option<BasicAuthCredentials>,
}

impl CommonHttpClient {
    fn is_channel_not_found(body: &str) -> bool {
        body.to_ascii_lowercase().contains("channel not found")
    }

    #[must_use]
    pub fn new(basic_auth: Option<BasicAuthCredentials>) -> Self {
        let initial_stream_window_size: u32 =
            u32::try_from(6 * default_max_body_size() / 10).unwrap_or(4 * 1025);
        let client = ClientBuilder::new()
            .http2_initial_stream_window_size(initial_stream_window_size)
            .build()
            .expect("Client from default settings should be able to build");
        Self {
            client: Arc::new(client),
            basic_auth,
        }
    }

    pub async fn post<Req, Res>(&self, request_url: Url, request_body: &Req) -> Result<Res, Error>
    where
        Req: Serialize + ?Sized + Send + Sync,
        Res: DeserializeOwned + Send + Sync,
    {
        let request = self.client.post(request_url).json(request_body);
        self.execute_request::<Res>(request).await
    }

    pub async fn get<Req, Res>(
        &self,
        request_url: Url,
        request_body: Option<&Req>,
    ) -> Result<Res, Error>
    where
        Req: Serialize + ?Sized + Send + Sync,
        Res: DeserializeOwned + Send + Sync,
    {
        let mut request = self.client.get(request_url);
        if let Some(request_body) = request_body {
            request = request.json(request_body);
        }
        self.execute_request::<Res>(request).await
    }

    pub async fn put<Req, Res>(
        &self,
        request_url: Url,
        request_body: Option<&Req>,
    ) -> Result<Res, Error>
    where
        Req: Serialize + ?Sized + Send + Sync,
        Res: DeserializeOwned + Send + Sync,
    {
        let mut request = self.client.put(request_url);
        if let Some(request_body) = request_body {
            request = request.json(request_body);
        }
        self.execute_request::<Res>(request).await
    }

    async fn execute_request<Res: DeserializeOwned>(
        &self,
        mut request: RequestBuilder,
    ) -> Result<Res, Error> {
        if let Some(basic_auth) = &self.basic_auth {
            request = request.basic_auth(&basic_auth.username, basic_auth.password.as_deref());
        }

        let response = request.send().await.map_err(Error::Request)?;
        let status = response.status();
        let body = response.text().await.map_err(Error::Request)?;

        match status {
            StatusCode::OK | StatusCode::CREATED => serde_json::from_str(&body)
                .map_err(|e| Error::Server(format!("Failed to parse response: {e}"))),
            StatusCode::INTERNAL_SERVER_ERROR => Err(Error::Server(body)),
            _ => Err(Error::Server(format!(
                "Unexpected response [{status}]: {body}",
            ))),
        }
    }

    pub async fn get_lib_stream(
        &self,
        base_url: Url,
    ) -> Result<impl Stream<Item = BlockInfo> + use<>, Error> {
        let request_url = base_url
            .join(CRYPTARCHIA_LIB_STREAM.trim_start_matches('/'))
            .map_err(Error::Url)?;
        let mut request = self.client.get(request_url);

        if let Some(basic_auth) = &self.basic_auth {
            request = request.basic_auth(&basic_auth.username, basic_auth.password.as_deref());
        }

        let response = request.send().await.map_err(Error::Request)?;
        let status = response.status();

        let lib_stream = response.bytes_stream().filter_map(async |item| {
            let bytes = item.ok()?;
            serde_json::from_slice::<BlockInfo>(&bytes).ok()
        });
        match status {
            StatusCode::OK => Ok(lib_stream),
            StatusCode::INTERNAL_SERVER_ERROR => Err(Error::Server("Error".to_owned())),
            _ => Err(Error::Server(format!("Unexpected response [{status}]"))),
        }
    }

    pub async fn get_block_by_id(
        &self,
        base_url: Url,
        id: HeaderId,
    ) -> Result<Option<ApiBlock>, Error> {
        let path = BLOCKS_DETAIL
            .trim_start_matches('/')
            .replace(":id", &id.to_string());
        let request_url = base_url.join(path.as_str()).map_err(Error::Url)?;

        let mut request = self.client.get(request_url);
        if let Some(basic_auth) = &self.basic_auth {
            request = request.basic_auth(&basic_auth.username, basic_auth.password.as_deref());
        }

        let response = request.send().await.map_err(Error::Request)?;
        let status = response.status();
        let body = response.text().await.map_err(Error::Request)?;

        match status {
            StatusCode::OK => serde_json::from_str::<ApiBlock>(&body)
                .map(Some)
                .map_err(|e| Error::Server(format!("Failed to parse response: {e}"))),
            StatusCode::NOT_FOUND => Ok(None),
            StatusCode::INTERNAL_SERVER_ERROR => Err(Error::Server(body)),
            _ => Err(Error::Server(format!(
                "Unexpected response [{status}]: {body}",
            ))),
        }
    }

    /// Get the events emitted by execution of a block by its id.
    pub async fn get_block_events(
        &self,
        base_url: Url,
        id: HeaderId,
    ) -> Result<Option<Events>, Error> {
        let path = BLOCK_EVENTS
            .trim_start_matches('/')
            .replace(":id", &id.to_string());
        let request_url = base_url.join(path.as_str()).map_err(Error::Url)?;

        let mut request = self.client.get(request_url);
        if let Some(basic_auth) = &self.basic_auth {
            request = request.basic_auth(&basic_auth.username, basic_auth.password.as_deref());
        }

        let response = request.send().await.map_err(Error::Request)?;
        let status = response.status();
        let body = response.text().await.map_err(Error::Request)?;

        match status {
            StatusCode::OK => serde_json::from_str::<Events>(&body)
                .map(Some)
                .map_err(|e| Error::Server(format!("Failed to parse response: {e}"))),
            StatusCode::NOT_FOUND => Ok(None),
            StatusCode::INTERNAL_SERVER_ERROR => Err(Error::Server(body)),
            _ => Err(Error::Server(format!(
                "Unexpected response [{status}]: {body}",
            ))),
        }
    }

    pub async fn post_transaction<Tx>(&self, base_url: Url, transaction: Tx) -> Result<(), Error>
    where
        Tx: Serialize + Send + Sync + 'static,
    {
        let request_url = base_url
            .join(MEMPOOL_ADD_TX.trim_start_matches('/'))
            .map_err(Error::Url)?;
        self.post(request_url, &transaction).await
    }

    /// Send a transaction through the Blend network, without adding it to the
    /// node's own mempool.
    ///
    /// The node it is submitted to never gossips the transaction itself — that
    /// would say where it came from — so it reaches the network blended, and
    /// comes back to this node's mempool like any other transaction once
    /// whichever node exits it gossips it on.
    ///
    /// Returns the transaction's id.
    pub async fn blend_transaction<Tx, Id>(
        &self,
        base_url: Url,
        transaction: Tx,
    ) -> Result<Id, Error>
    where
        Tx: Serialize + Send + Sync + 'static,
        Id: for<'de> Deserialize<'de> + Send + Sync,
    {
        let request_url = base_url
            .join(BLEND_DISPERSE_TRANSACTION.trim_start_matches('/'))
            .map_err(Error::Url)?;
        self.post(request_url, &transaction).await
    }

    /// The ids of the transactions the node is still waiting on a `PoW`
    /// solution for before it can blend them.
    pub async fn blend_pending_transactions<Id>(&self, base_url: Url) -> Result<Vec<Id>, Error>
    where
        Id: for<'de> Deserialize<'de> + Send + Sync,
    {
        let request_url = base_url
            .join(BLEND_PENDING_TRANSACTIONS.trim_start_matches('/'))
            .map_err(Error::Url)?;
        self.get::<(), _>(request_url, None).await
    }

    /// Post a service declaration to the SDP endpoint.
    pub async fn post_declaration(
        &self,
        base_url: Url,
        declaration: &DeclarationMessage,
    ) -> Result<DeclarationId, Error> {
        let request_url = base_url
            .join(SDP_POST_DECLARATION.trim_start_matches('/'))
            .map_err(Error::Url)?;
        self.post(request_url, declaration).await
    }

    /// Get the version of the node, e.g. `0.1.2 (abcdefaa)`.
    pub async fn get_node_version(&self, base_url: Url) -> Result<String, Error> {
        let request_url = base_url
            .join(NODE_VERSION.trim_start_matches('/'))
            .map_err(Error::Url)?;
        self.get::<(), String>(request_url, None).await
    }

    /// Get consensus info (tip, height, etc.)
    pub async fn consensus_info(&self, base_url: Url) -> Result<ChainServiceInfo, Error> {
        let request_url = base_url
            .join(CRYPTARCHIA_INFO.trim_start_matches('/'))
            .map_err(Error::Url)?;
        self.get::<(), ChainServiceInfo>(request_url, None).await
    }

    /// Get the gas prices from the ledger state at `tip`, or at the current
    /// tip when `tip` is `None`.
    pub async fn gas_prices(
        &self,
        base_url: Url,
        tip: Option<HeaderId>,
    ) -> Result<GasPricesResponseBody, Error> {
        let mut request_url = base_url
            .join(MANTLE_GAS_PRICES.trim_start_matches('/'))
            .map_err(Error::Url)?;

        if let Some(t) = tip {
            request_url
                .query_pairs_mut()
                .append_pair("tip", &t.to_string());
        }

        self.get::<(), GasPricesResponseBody>(request_url, None)
            .await
    }

    /// Get time service info derived from deployment settings.
    pub async fn time_info(&self, base_url: Url) -> Result<TimeInfo, Error> {
        let request_url = base_url
            .join(TIME_INFO.trim_start_matches('/'))
            .map_err(Error::Url)?;
        self.get::<(), TimeInfo>(request_url, None).await
    }

    /// Get channel state for a specific channel id.
    pub async fn channel_state(
        &self,
        base_url: Url,
        channel_id: ChannelId,
    ) -> Result<Option<ChannelState>, Error> {
        let path = CHANNEL
            .trim_start_matches('/')
            .replace(":id", &hex::encode(channel_id.as_ref()));
        let request_url = base_url.join(path.as_str()).map_err(Error::Url)?;

        let mut request = self.client.get(request_url);
        if let Some(basic_auth) = &self.basic_auth {
            request = request.basic_auth(&basic_auth.username, basic_auth.password.as_deref());
        }

        let response = request.send().await.map_err(Error::Request)?;
        let status = response.status();
        let body = response.text().await.map_err(Error::Request)?;

        match status {
            StatusCode::OK => serde_json::from_str::<ChannelState>(&body)
                .map(Some)
                .map_err(|e| Error::Server(format!("Failed to parse response: {e}"))),
            StatusCode::NOT_FOUND => Ok(None),
            StatusCode::INTERNAL_SERVER_ERROR if Self::is_channel_not_found(&body) => Ok(None),
            StatusCode::INTERNAL_SERVER_ERROR => Err(Error::Server(body)),
            _ if Self::is_channel_not_found(&body) => Ok(None),
            _ => Err(Error::Server(format!(
                "Unexpected response [{status}]: {body}",
            ))),
        }
    }

    /// Get immutable blocks in a slot range.
    pub async fn get_immutable_blocks(
        &self,
        base_url: Url,
        slot_from: u64,
        slot_to: u64,
    ) -> Result<Vec<ApiBlock>, Error> {
        let mut request_url = base_url
            .join(BLOCKS.trim_start_matches('/'))
            .map_err(Error::Url)?;
        request_url
            .query_pairs_mut()
            .append_pair("slot_from", &slot_from.to_string())
            .append_pair("slot_to", &slot_to.to_string());
        self.get::<(), Vec<ApiBlock>>(request_url, None).await
    }

    /// Subscribe to the processed blocks stream.
    /// Each event contains the block, current tip, and current LIB.
    pub async fn get_blocks_stream(
        &self,
        base_url: Url,
    ) -> Result<impl Stream<Item = ProcessedBlockEvent> + use<>, Error> {
        let request_url = base_url
            .join(BLOCKS_STREAM.trim_start_matches('/'))
            .map_err(Error::Url)?;
        let mut request = self.client.get(request_url);

        if let Some(basic_auth) = &self.basic_auth {
            request = request.basic_auth(&basic_auth.username, basic_auth.password.as_deref());
        }

        let response = request.send().await.map_err(Error::Request)?;
        let status = response.status();

        let blocks_stream = response.bytes_stream().filter_map(async |item| {
            let bytes = item.ok()?;
            serde_json::from_slice::<ProcessedBlockEvent>(&bytes).ok()
        });
        match status {
            StatusCode::OK => Ok(blocks_stream),
            StatusCode::INTERNAL_SERVER_ERROR => Err(Error::Server("Error".to_owned())),
            _ => Err(Error::Server(format!("Unexpected response [{status}]"))),
        }
    }

    /// Build the request URL for the `get_blocks_range_stream` method with the
    /// given parameters.
    pub fn build_blocks_range_stream_request_url(
        base_url: &Url,
        params: &BlocksStreamQuery,
    ) -> Result<Url, Error> {
        let mut request_url = base_url
            .join(BLOCKS_RANGE_STREAM.trim_start_matches('/'))
            .map_err(Error::Url)?;
        params.append_to_url(&mut request_url);
        Ok(request_url)
    }

    async fn send_blocks_range_stream_request(
        &self,
        request_url: Url,
    ) -> Result<reqwest::Response, Error> {
        let mut request = self.client.get(request_url);
        if let Some(basic_auth) = &self.basic_auth {
            request = request.basic_auth(&basic_auth.username, basic_auth.password.as_deref());
        }

        let response = request.send().await.map_err(Error::Request)?;
        let status = response.status();
        let response_url = response.url().clone();

        if status != StatusCode::OK {
            let body = response.text().await.map_err(Error::Request)?;
            return match status {
                StatusCode::INTERNAL_SERVER_ERROR => {
                    Err(Error::Server(format!("{body} [{response_url}]")))
                }
                _ => Err(Error::Server(format!(
                    "Unexpected response [{status}] at [{response_url}]: {body}"
                ))),
            };
        }

        Ok(response)
    }

    // Helper function to validate inputs for block streaming methods.
    fn verify_inputs(
        blocks_limit: Option<std::num::NonZero<usize>>,
        slot_from: Option<u64>,
        slot_to: Option<u64>,
        server_batch_size: Option<std::num::NonZero<usize>>,
    ) -> Result<(), Error> {
        if let Some(blocks) = blocks_limit
            && blocks.get() > MAX_BLOCKS_STREAM_BLOCKS
        {
            return Err(Error::Client(format!(
                "'blocks_limit' must be <= {MAX_BLOCKS_STREAM_BLOCKS}, got {blocks}"
            )));
        }
        if let Some(size) = server_batch_size
            && size.get() > MAX_BLOCKS_STREAM_CHUNK_SIZE
        {
            return Err(Error::Client(format!(
                "'server_batch_size' must be <= {MAX_BLOCKS_STREAM_CHUNK_SIZE}, got {size}"
            )));
        }
        if let (Some(slot_from), Some(slot_to)) = (slot_from, slot_to)
            && slot_from > slot_to
        {
            return Err(Error::Client(format!(
                "'slot_from' must be <= 'slot_to', got slot_from={slot_from}, slot_to={slot_to}"
            )));
        }

        Ok(())
    }

    /// Stream processed blocks in a slot-bounded window.
    ///
    /// `server_batch_size` lets callers request smaller chunks; the server
    /// still enforces its own upper bound.
    pub async fn get_blocks_range_stream(
        &self,
        base_url: Url,
        params: BlocksStreamQuery,
    ) -> Result<impl Stream<Item = ProcessedBlockEvent> + use<>, Error> {
        let request_url = Self::build_blocks_range_stream_request_url(&base_url, &params)?;
        Self::verify_inputs(
            params.blocks_limit,
            params.slot_from,
            params.slot_to,
            params.server_batch_size,
        )?;
        let response = self.send_blocks_range_stream_request(request_url).await?;
        Ok(Self::parse_processed_blocks_range_event_stream(response))
    }

    fn parse_processed_blocks_range_event_stream(
        response: reqwest::Response,
    ) -> impl Stream<Item = ProcessedBlockEvent> {
        // NDJSON event upper bound; margin above max serialized single event line
        const MAX_NDJSON_LINE_BYTES: usize = MAX_BLOCK_TRANSACTIONS_SIZE * 3 / 2;
        const LOG_LINE_PREVIEW_CHARS: usize = 256;

        let byte_stream = response.bytes_stream().map_err(std::io::Error::other);
        let reader = StreamReader::new(byte_stream);
        let codec = LinesCodec::new_with_max_length(MAX_NDJSON_LINE_BYTES);
        let lines = FramedRead::new(reader, codec);

        lines.filter_map(async |line_result| match line_result {
            Ok(line) => {
                if line.is_empty() {
                    return None;
                }

                match serde_json::from_str::<ProcessedBlockEvent>(&line) {
                    Ok(event) => Some(event),
                    Err(err) => {
                        let preview: String = line.chars().take(LOG_LINE_PREVIEW_CHARS).collect();
                        warn!(
                            target: LOG_TARGET,
                            "blocks stream JSON decode failed: {err}; line_preview={preview:?}"
                        );
                        None
                    }
                }
            }
            Err(err) => {
                warn!(target: LOG_TARGET, "blocks stream line decode failed: {err}");
                None
            }
        })
    }

    /// Get the balance for a specific `ZkPublicKey`.
    pub async fn get_wallet_balance(
        &self,
        base_url: Url,
        zk_pk: ZkPublicKey,
        tip: Option<HeaderId>,
    ) -> Result<WalletBalanceResponseBody, Error> {
        let key_id = hex::encode(fr_to_bytes(zk_pk.as_fr()));
        let mut request_url = base_url
            .join(&BALANCE.replace(":public_key", &key_id))
            .map_err(Error::Url)?;

        if let Some(t) = tip {
            request_url
                .query_pairs_mut()
                .append_pair("tip", &t.to_string());
        }

        self.get::<(), WalletBalanceResponseBody>(request_url, None)
            .await
    }

    /// Get claimable reward vouchers tracked by the wallet.
    pub async fn get_claimable_vouchers(
        &self,
        base_url: Url,
        tip: Option<HeaderId>,
    ) -> Result<WalletClaimableVouchersResponseBody, Error> {
        let mut request_url = base_url
            .join(LEADER_CLAIM_VOUCHERS.trim_start_matches('/'))
            .map_err(Error::Url)?;

        if let Some(t) = tip {
            request_url
                .query_pairs_mut()
                .append_pair("tip", &t.to_string());
        }

        self.get::<(), WalletClaimableVouchersResponseBody>(request_url, None)
            .await
    }

    /// Post a request to transfer funds.
    pub async fn transfer_funds(
        &self,
        base_url: Url,
        body: WalletTransferFundsRequestBody,
    ) -> Result<WalletTransferFundsResponseBody, Error> {
        let request_url = base_url
            .join(TRANSACTIONS_TRANSFER_FUNDS.trim_start_matches('/'))
            .map_err(Error::Url)?;

        self.post(request_url, &body).await
    }

    /// Post a request to fund a transaction from the node's wallet.
    ///
    /// The node adds fee inputs and change from its own wallet, reserving the
    /// request's percentage-based priority-fee reserve, then signs only the
    /// appended fee transfer and returns the funded (still unsigned)
    /// transaction together with the transfer proof.
    pub async fn fund_tx(
        &self,
        base_url: Url,
        body: WalletFundRequestBody,
    ) -> Result<WalletFundResponseBody, Error> {
        let request_url = base_url
            .join(FUND.trim_start_matches('/'))
            .map_err(Error::Url)?;

        self.post(request_url, &body).await
    }

    /// Post a request via an SDP declaration to join the blend network and
    /// returns its declaration ID if successful.
    pub async fn join_blend_network(
        &self,
        base_url: &Url,
        body: JoinBlendRequestBody,
    ) -> Result<DeclarationId, Error> {
        let request_url = base_url
            .join(BLEND_JOIN_NETWORK.trim_start_matches('/'))
            .map_err(Error::Url)?;

        self.post(request_url, &body).await
    }
}