// file: crates/ksp-offchain-transport-lib/src/market_price_kraken.rs
// version: 1

//! Kraken Spot SOL/USD market-price adapter using the public REST ticker directly through `reqwest`.

const KRAKEN_PROVIDER_ID: &str = "kraken";
const KRAKEN_SOL_USD_PAIR: &str = "SOLUSD";
const KRAKEN_TICKER_URL: &str = "https://api.kraken.com/0/public/Ticker";

/// Runtime settings for the keyless Kraken Spot market-price adapter.
#[derive(Clone, Debug, Eq, PartialEq)]
pub struct MarketPriceKrakenSettings {
    common: crate::MarketPriceProviderCommonSettings,
}

impl crate::MarketPriceKrakenSettings {
    /// Creates Kraken Spot settings for the public keyless REST surface.
    pub fn new(enabled: bool) -> ksp_core_lib::Result<Self> {
        let provider_id = match crate::MarketPriceProviderId::new(KRAKEN_PROVIDER_ID) {
            std::result::Result::Ok(value) => value,
            std::result::Result::Err(error) => return std::result::Result::Err(error),
        };
        return std::result::Result::Ok(Self { common: crate::MarketPriceProviderCommonSettings::new(provider_id, enabled) });
    }

    /// Returns common provider identity and enablement settings.
    #[must_use]
    pub const fn common(&self) -> &crate::MarketPriceProviderCommonSettings {
        return &self.common;
    }
}

/// Kraken Spot SOL/USD provider adapter.
pub struct MarketPriceKrakenProvider {
    admission: crate::HttpAdmissionController,
    descriptor: crate::MarketPriceProviderDescriptor,
    http: crate::HttpRestClient,
    settings: crate::MarketPriceKrakenSettings,
}

impl crate::MarketPriceKrakenProvider {
    /// Builds one Kraken Spot provider from validated runtime settings.
    pub fn new(settings: crate::MarketPriceKrakenSettings) -> ksp_core_lib::Result<Self> {
        let descriptor = match descriptor_for(settings.common().provider_id().clone()) {
            std::result::Result::Ok(value) => value,
            std::result::Result::Err(error) => return std::result::Result::Err(error),
        };
        let runtime = match crate::provider_http_runtime(descriptor.rate_limit()) {
            std::result::Result::Ok(value) => value,
            std::result::Result::Err(error) => return std::result::Result::Err(error),
        };
        return std::result::Result::Ok(Self { admission: runtime.1, descriptor, http: runtime.0, settings });
    }

    /// Returns the provider-neutral Kraken Spot capability descriptor.
    #[must_use]
    pub const fn descriptor(&self) -> &crate::MarketPriceProviderDescriptor {
        return &self.descriptor;
    }

    /// Returns the validated Kraken Spot runtime settings.
    #[must_use]
    pub const fn settings(&self) -> &crate::MarketPriceKrakenSettings {
        return &self.settings;
    }

    /// Fetches one normalized SOL/USD last-trade observation from Kraken Spot.
    pub async fn fetch_sol_usd(&self) -> ksp_core_lib::Result<crate::MarketPriceObservation> {
        if !self.settings.common().enabled() {
            return std::result::Result::Err(crate::provider_disabled_error(KRAKEN_PROVIDER_ID));
        }
        if let std::result::Result::Err(error) = crate::admit_request(KRAKEN_PROVIDER_ID, &self.admission) {
            return std::result::Result::Err(error);
        }
        let request_started_at = match crate::current_timestamp() {
            std::result::Result::Ok(value) => value,
            std::result::Result::Err(error) => return std::result::Result::Err(error),
        };
        let request = match build_request() {
            std::result::Result::Ok(value) => value,
            std::result::Result::Err(error) => return std::result::Result::Err(error),
        };
        let document = match crate::get_json(&self.http, &self.admission, KRAKEN_PROVIDER_ID, request).await {
            std::result::Result::Ok(value) => value,
            std::result::Result::Err(error) => return std::result::Result::Err(error),
        };
        let received_at = match crate::current_timestamp() {
            std::result::Result::Ok(value) => value,
            std::result::Result::Err(error) => return std::result::Result::Err(error),
        };
        return parse_response(document.as_bytes(), self.settings.common().provider_id().clone(), request_started_at, received_at);
    }
}

fn build_request() -> ksp_core_lib::Result<crate::HttpGetRequest> {
    let mut request = match crate::HttpGetRequest::new_https(KRAKEN_TICKER_URL) {
        std::result::Result::Ok(value) => value,
        std::result::Result::Err(error) => return std::result::Result::Err(error),
    };
    request.append_query_pair("pair", KRAKEN_SOL_USD_PAIR);
    return std::result::Result::Ok(request);
}

fn descriptor_for(provider_id: crate::MarketPriceProviderId) -> ksp_core_lib::Result<crate::MarketPriceProviderDescriptor> {
    let rate_limit = match crate::MarketPriceProviderRateLimit::fixed(1, 1, std::option::Option::None, crate::MarketPriceProviderRateLimitScope::Ip) {
        std::result::Result::Ok(value) => value,
        std::result::Result::Err(error) => return std::result::Result::Err(error),
    };
    return crate::MarketPriceProviderDescriptor::new(
        provider_id,
        "Kraken",
        crate::MarketPriceSemantics::ExchangeLastTrade,
        crate::MarketPriceProviderAuthMode::None,
        rate_limit,
        std::option::Option::None,
        true,
    );
}

fn parse_response(
    bytes: &[u8],
    provider_id: crate::MarketPriceProviderId,
    request_started_at: crate::MarketPriceTimestamp,
    received_at: crate::MarketPriceTimestamp,
) -> ksp_core_lib::Result<crate::MarketPriceObservation> {
    let wire = match serde_json::from_slice::<KrakenWireResponse>(bytes) {
        std::result::Result::Ok(value) => value,
        std::result::Result::Err(error) => {
            return std::result::Result::Err(crate::invalid_provider_response_with_source(KRAKEN_PROVIDER_ID, "response", error));
        },
    };
    if !wire.error.is_empty() {
        return std::result::Result::Err(crate::invalid_provider_response(KRAKEN_PROVIDER_ID, "error"));
    }
    if wire.result.len() != 1 {
        return std::result::Result::Err(crate::invalid_provider_response(KRAKEN_PROVIDER_ID, "result"));
    }
    let ticker = match wire.result.get(KRAKEN_SOL_USD_PAIR) {
        std::option::Option::Some(value) => value,
        std::option::Option::None => return std::result::Result::Err(crate::invalid_provider_response(KRAKEN_PROVIDER_ID, "identity")),
    };
    let last_trade = match ticker.last_trade.first() {
        std::option::Option::Some(value) => value,
        std::option::Option::None => return std::result::Result::Err(crate::invalid_provider_response(KRAKEN_PROVIDER_ID, "last_trade")),
    };
    let price = match crate::MarketPriceDecimal::parse_json_raw(last_trade.as_ref()) {
        std::result::Result::Ok(value) => value,
        std::result::Result::Err(error) => return std::result::Result::Err(error),
    };
    let provenance = match crate::MarketPriceProvenance::new("kraken:SOLUSD:last_trade") {
        std::result::Result::Ok(value) => value,
        std::result::Result::Err(error) => return std::result::Result::Err(error),
    };
    return crate::MarketPriceObservation::new(
        provider_id,
        price,
        crate::MarketPriceSemantics::ExchangeLastTrade,
        request_started_at,
        received_at,
        std::option::Option::None,
        provenance,
    );
}

#[derive(serde::Deserialize)]
struct KrakenWireResponse {
    error: std::vec::Vec<std::string::String>,
    result: std::collections::BTreeMap<std::string::String, KrakenWireTicker>,
}

#[derive(serde::Deserialize)]
struct KrakenWireTicker {
    #[serde(rename = "c")]
    last_trade: std::vec::Vec<std::boxed::Box<serde_json::value::RawValue>>,
}

#[cfg(test)]
#[path = "../unit_tests/market_price_kraken.rs"]
mod tests;