use once_cell::sync::Lazy;
use reqwest::get;
use semver::Version;
use serde::{
    de::{self, Deserializer},
    Deserialize, Serialize,
};
use std::collections::BTreeMap;
use url::Url;

use crate::{error::SolcVmError, platform::Platform};

const SOLC_RELEASES_URL: &str = "https://binaries.soliditylang.org";

const OLD_SOLC_RELEASES_DOWNLOAD_PREFIX: &str =
    "https://raw.githubusercontent.com/crytic/solc/master/linux/amd64";

static OLD_VERSION_MAX: Lazy<Version> = Lazy::new(|| Version::new(0, 4, 9));

static OLD_VERSION_MIN: Lazy<Version> = Lazy::new(|| Version::new(0, 4, 0));

static OLD_SOLC_RELEASES: Lazy<Releases> = Lazy::new(|| {
    serde_json::from_str(include_str!("../list/linux-arm64-old.json"))
        .expect("could not parse list linux-arm64-old.json")
});

static LINUX_AARCH64_MIN: Lazy<Version> = Lazy::new(|| Version::new(0, 5, 0));

static LINUX_AARCH64_URL_PREFIX: &str =
    "https://github.com/nikitastupin/solc/raw/0e071f4e18220d314689d4742e22e0ca5dfc13f6/linux/aarch64";

static LINUX_AARCH64_RELEASES_URL: &str =
    "https://github.com/nikitastupin/solc/raw/0e071f4e18220d314689d4742e22e0ca5dfc13f6/linux/aarch64/list.json";

static MACOS_AARCH64_NATIVE: Lazy<Version> = Lazy::new(|| Version::new(0, 8, 5));

static MACOS_AARCH64_URL_PREFIX: &str =
    "https://github.com/ethers-rs/solc-builds/raw/5560a1f4b69f081d120b0df1735bf87cdda2e6b5/macosx/aarch64";

static MACOS_AARCH64_RELEASES_URL: &str =
    "https://github.com/ethers-rs/solc-builds/raw/5560a1f4b69f081d120b0df1735bf87cdda2e6b5/macosx/aarch64/list.json";

/// Defines the struct that the JSON-formatted release list can be deserialized into.
///
/// {
///     "builds": [
///         {
///             "version": "0.8.7",
///             "sha256": "0x0xcc5c663d1fe17d4eb4aca09253787ac86b8785235fca71d9200569e662677990"
///         }
///     ]
///     "releases": {
///         "0.8.7": "solc-macosx-amd64-v0.8.7+commit.e28d00a7",
///         "0.8.6": "solc-macosx-amd64-v0.8.6+commit.11564f7e",
///         ...
///     }
/// }
///
/// Both the key and value are deserialized into semver::Version.
#[derive(Clone, Debug, PartialEq, Eq, Default, Serialize, Deserialize)]
pub struct Releases {
    pub builds: Vec<BuildInfo>,
    pub releases: BTreeMap<Version, String>,
}

impl Releases {
    /// Get the checksum of a solc version's binary if it exists.
    pub fn get_checksum(&self, v: &Version) -> Option<Vec<u8>> {
        for build in self.builds.iter() {
            if build.version.eq(v) {
                return Some(build.sha256.clone());
            }
        }
        None
    }

    /// Returns the artifact of the version if any
    pub fn get_artifact(&self, version: &Version) -> Option<&String> {
        self.releases.get(version)
    }

    /// Returns a sorted list of all versions
    pub fn into_versions(self) -> Vec<Version> {
        let mut versions = self.releases.into_keys().collect::<Vec<_>>();
        versions.sort_unstable();
        versions
    }
}

/// Build info contains the SHA256 checksum of a solc binary.
#[derive(Clone, Debug, PartialEq, Eq, Serialize, Deserialize)]
pub struct BuildInfo {
    pub version: Version,
    #[serde(with = "hex_string")]
    pub sha256: Vec<u8>,
}

/// Helper serde module to serialize and deserialize bytes as hex.
mod hex_string {
    use super::*;
    use serde::Serializer;
    pub fn deserialize<'de, D>(deserializer: D) -> Result<Vec<u8>, D::Error>
    where
        D: Deserializer<'de>,
    {
        let str_hex = String::deserialize(deserializer)?;
        let str_hex = str_hex.trim_start_matches("0x");
        hex::decode(str_hex).map_err(|err| de::Error::custom(err.to_string()))
    }

    pub fn serialize<T, S>(value: &T, serializer: S) -> Result<S::Ok, S::Error>
    where
        S: Serializer,
        T: AsRef<[u8]>,
    {
        let value = hex::encode(value);
        serializer.serialize_str(&value)
    }
}

/// Blocking version fo [`all_realeases`]
#[cfg(feature = "blocking")]
pub fn blocking_all_releases(platform: Platform) -> Result<Releases, SolcVmError> {
    if platform == Platform::LinuxAarch64 {
        return Ok(reqwest::blocking::get(LINUX_AARCH64_RELEASES_URL)?.json::<Releases>()?);
    }

    if platform == Platform::MacOsAarch64 {
        // The supported versions for both macos-amd64 and macos-aarch64 are the same.
        //
        // 1. For version >= 0.8.5 we fetch native releases from
        // https://github.com/ethers-rs/solc-builds
        //
        // 2. For version <= 0.8.4 we fetch releases from https://binaries.soliditylang.org and
        // require Rosetta support.
        let mut native = reqwest::blocking::get(MACOS_AARCH64_RELEASES_URL)?.json::<Releases>()?;
        let mut releases = reqwest::blocking::get(format!(
            "{}/{}/list.json",
            SOLC_RELEASES_URL,
            Platform::MacOsAmd64,
        ))?
        .json::<Releases>()?;
        releases
            .builds
            .retain(|b| b.version.lt(&MACOS_AARCH64_NATIVE));
        releases.builds.extend_from_slice(&native.builds);
        releases.releases.append(&mut native.releases);
        return Ok(releases);
    }

    let releases = reqwest::blocking::get(format!("{SOLC_RELEASES_URL}/{platform}/list.json"))?
        .json::<Releases>()?;
    Ok(unified_releases(releases, platform))
}

/// Fetch all releases available for the provided platform.
pub async fn all_releases(platform: Platform) -> Result<Releases, SolcVmError> {
    if platform == Platform::LinuxAarch64 {
        return Ok(get(LINUX_AARCH64_RELEASES_URL)
            .await?
            .json::<Releases>()
            .await?);
    }

    if platform == Platform::MacOsAarch64 {
        // The supported versions for both macos-amd64 and macos-aarch64 are the same.
        //
        // 1. For version >= 0.8.5 we fetch native releases from
        // https://github.com/ethers-rs/solc-builds
        //
        // 2. For version <= 0.8.4 we fetch releases from https://binaries.soliditylang.org and
        // require Rosetta support.
        let mut native = get(MACOS_AARCH64_RELEASES_URL)
            .await?
            .json::<Releases>()
            .await?;
        let mut releases = get(format!(
            "{}/{}/list.json",
            SOLC_RELEASES_URL,
            Platform::MacOsAmd64,
        ))
        .await?
        .json::<Releases>()
        .await?;
        releases
            .builds
            .retain(|b| b.version.lt(&MACOS_AARCH64_NATIVE));
        releases.releases.retain(|v, _| v.lt(&MACOS_AARCH64_NATIVE));

        releases.builds.extend_from_slice(&native.builds);
        releases.releases.append(&mut native.releases);
        return Ok(releases);
    }

    let releases = get(format!("{SOLC_RELEASES_URL}/{platform}/list.json"))
        .await?
        .json::<Releases>()
        .await?;

    Ok(unified_releases(releases, platform))
}

/// unifies the releases with old releases if on linux
fn unified_releases(releases: Releases, platform: Platform) -> Releases {
    if platform == Platform::LinuxAmd64 {
        let mut all_releases = OLD_SOLC_RELEASES.clone();
        all_releases.builds.extend(releases.builds);
        all_releases.releases.extend(releases.releases);
        all_releases
    } else {
        releases
    }
}

/// Construct the URL to the Solc binary for the specified release version and target platform.
pub fn artifact_url(
    platform: Platform,
    version: &Version,
    artifact: &str,
) -> Result<Url, SolcVmError> {
    if platform == Platform::LinuxAmd64
        && version.le(&OLD_VERSION_MAX)
        && version.ge(&OLD_VERSION_MIN)
    {
        return Ok(Url::parse(&format!(
            "{OLD_SOLC_RELEASES_DOWNLOAD_PREFIX}/{artifact}"
        ))?);
    }

    if platform == Platform::LinuxAarch64 {
        if version.ge(&LINUX_AARCH64_MIN) {
            return Ok(Url::parse(&format!(
                "{LINUX_AARCH64_URL_PREFIX}/{artifact}"
            ))?);
        } else {
            return Err(SolcVmError::UnsupportedVersion(
                version.to_string(),
                platform.to_string(),
            ));
        }
    }

    if platform == Platform::MacOsAmd64 && version.lt(&OLD_VERSION_MIN) {
        return Err(SolcVmError::UnsupportedVersion(
            version.to_string(),
            platform.to_string(),
        ));
    }

    if platform == Platform::MacOsAarch64 {
        if version.ge(&MACOS_AARCH64_NATIVE) {
            return Ok(Url::parse(&format!(
                "{MACOS_AARCH64_URL_PREFIX}/{artifact}"
            ))?);
        } else {
            return Ok(Url::parse(&format!(
                "{}/{}/{}",
                SOLC_RELEASES_URL,
                Platform::MacOsAmd64,
                artifact,
            ))?);
        }
    }

    Ok(Url::parse(&format!(
        "{SOLC_RELEASES_URL}/{platform}/{artifact}"
    ))?)
}

#[cfg(test)]
mod tests {
    use super::*;

    #[test]
    fn test_old_releases_deser() {
        assert_eq!(OLD_SOLC_RELEASES.releases.len(), 10);
        assert_eq!(OLD_SOLC_RELEASES.builds.len(), 10);
    }

    #[tokio::test]
    async fn test_macos_aarch64() {
        let releases = all_releases(Platform::MacOsAarch64)
            .await
            .expect("could not fetch releases for macos-aarch64");
        let rosetta = Version::new(0, 8, 4);
        let native = MACOS_AARCH64_NATIVE.clone();
        let url1 = artifact_url(
            Platform::MacOsAarch64,
            &rosetta,
            releases.get_artifact(&rosetta).unwrap(),
        )
        .expect("could not fetch artifact URL");
        let url2 = artifact_url(
            Platform::MacOsAarch64,
            &native,
            releases.get_artifact(&native).unwrap(),
        )
        .expect("could not fetch artifact URL");
        assert!(url1.to_string().contains(SOLC_RELEASES_URL));
        assert!(url2.to_string().contains(MACOS_AARCH64_URL_PREFIX));
    }

    #[tokio::test]
    async fn test_all_releases_macos_amd64() {
        assert!(all_releases(Platform::MacOsAmd64).await.is_ok());
    }

    #[tokio::test]
    async fn test_all_releases_macos_aarch64() {
        assert!(all_releases(Platform::MacOsAarch64).await.is_ok());
    }

    #[tokio::test]
    async fn test_all_releases_linux_amd64() {
        assert!(all_releases(Platform::LinuxAmd64).await.is_ok());
    }

    #[tokio::test]
    async fn test_all_releases_linux_aarch64() {
        assert!(all_releases(Platform::LinuxAarch64).await.is_ok());
    }

    #[tokio::test]
    async fn releases_roundtrip() {
        let releases = all_releases(Platform::LinuxAmd64).await.unwrap();
        let s = serde_json::to_string(&releases).unwrap();
        let de_releases: Releases = serde_json::from_str(&s).unwrap();
        assert_eq!(releases, de_releases);
    }
}