//! Module implements reading of contract artifacts from various sources.
use super::util;
use ethers_core::types::Address;

use crate::util::resolve_path;
use cfg_if::cfg_if;
use eyre::{eyre, Context, Error, Result};
use std::{env, fs, path::Path, str::FromStr};
use url::Url;

/// A source of a Truffle artifact JSON.
#[derive(Clone, Debug, Eq, PartialEq)]
pub enum Source {
    /// A raw ABI string
    String(String),

    /// An ABI located on the local file system.
    Local(String),

    /// An ABI to be retrieved over HTTP(S).
    Http(Url),

    /// An address of a mainnet contract that has been verified on Etherscan.io.
    Etherscan(Address),

    /// An address of a mainnet contract that has been verified on Polygonscan.com.
    Polygonscan(Address),

    /// An address of a mainnet contract that has been verified on snowtrace.io.
    Snowtrace(Address),

    /// The package identifier of an npm package with a path to a Truffle
    /// artifact or ABI to be retrieved from `unpkg.io`.
    Npm(String),
}

impl Source {
    /// Parses an ABI from a source
    ///
    /// Contract ABIs can be retrieved from the local filesystem or online
    /// from `etherscan.io`. They can also be provided in-line. This method parses
    /// ABI source URLs and accepts the following:
    ///
    /// - raw ABI JSON
    ///
    /// - `relative/path/to/Contract.json`: a relative path to an ABI JSON file.
    /// This relative path is rooted in the current working directory.
    /// To specify the root for relative paths, use `Source::with_root`.
    ///
    /// - `/absolute/path/to/Contract.json` or `file:///absolute/path/to/Contract.json`: an absolute
    ///   path or file URL to an ABI JSON file.
    ///
    /// - `http(s)://...` an HTTP url to a contract ABI.
    ///
    /// - `etherscan:0xXX..XX` or `https://etherscan.io/address/0xXX..XX`: a address or URL of a
    ///   verified contract on Etherscan.
    ///
    /// - `npm:@org/package@1.0.0/path/to/contract.json` an npmjs package with an optional version
    ///   and path (defaulting to the latest version and `index.js`). The contract ABI will be
    ///   retrieved through `unpkg.io`.
    pub fn parse<S>(source: S) -> Result<Self>
    where
        S: AsRef<str>,
    {
        let source = source.as_ref();
        if matches!(source.chars().next(), Some('[' | '{')) {
            return Ok(Source::String(source.to_owned()))
        }
        let root = env::var("CARGO_MANIFEST_DIR")?;
        Source::with_root(root, source)
    }

    /// Parses an artifact source from a string and a specified root directory
    /// for resolving relative paths. See `Source::with_root` for more details
    /// on supported source strings.
    fn with_root<P, S>(root: P, source: S) -> Result<Self>
    where
        P: AsRef<Path>,
        S: AsRef<str>,
    {
        let source = source.as_ref();
        let root = root.as_ref();
        cfg_if! {
            if #[cfg(target_arch = "wasm32")] {
                let root = if root.starts_with("/") {
                    format!("file:://{}", root.display())
                } else {
                    format!("{}", root.display())
                };
                let base = Url::parse(&root)
                    .map_err(|_| eyre!("root path '{}' is not absolute", root))?;
            } else {
                let base = Url::from_directory_path(root)
                    .map_err(|_| eyre!("root path '{}' is not absolute", root.display()))?;
            }
        }
        let url = base.join(source)?;

        match url.scheme() {
            "file" => Ok(Source::local(source)),
            "http" | "https" => match url.host_str() {
                Some("etherscan.io") => Source::etherscan(
                    url.path()
                        .rsplit('/')
                        .next()
                        .ok_or_else(|| eyre!("HTTP URL does not have a path"))?,
                ),
                Some("polygonscan.com") => Source::polygonscan(
                    url.path()
                        .rsplit('/')
                        .next()
                        .ok_or_else(|| eyre!("HTTP URL does not have a path"))?,
                ),
                Some("snowtrace.io") => Source::snowtrace(
                    url.path()
                        .rsplit('/')
                        .next()
                        .ok_or_else(|| eyre!("HTTP URL does not have a path"))?,
                ),
                _ => Ok(Source::Http(url)),
            },
            "etherscan" => Source::etherscan(url.path()),
            "polygonscan" => Source::polygonscan(url.path()),
            "snowtrace" => Source::snowtrace(url.path()),
            "npm" => Ok(Source::npm(url.path())),
            _ => Err(eyre!("unsupported URL '{}'", url)),
        }
    }

    /// Creates a local filesystem source from a path string.
    pub fn local(path: impl Into<String>) -> Self {
        Source::Local(path.into())
    }

    /// Creates an HTTP source from a URL.
    pub fn http<S>(url: S) -> Result<Self>
    where
        S: AsRef<str>,
    {
        Ok(Source::Http(Url::parse(url.as_ref())?))
    }

    /// Creates an Etherscan source from an address string.
    pub fn etherscan<S>(address: S) -> Result<Self>
    where
        S: AsRef<str>,
    {
        let address =
            util::parse_address(address).context("failed to parse address for Etherscan source")?;
        Ok(Source::Etherscan(address))
    }

    /// Creates an Polygonscan source from an address string.
    pub fn polygonscan<S>(address: S) -> Result<Self>
    where
        S: AsRef<str>,
    {
        let address = util::parse_address(address)
            .context("failed to parse address for Polygonscan source")?;
        Ok(Source::Polygonscan(address))
    }

    /// Creates an Snowtrace source from an address string.
    pub fn snowtrace<S>(address: S) -> Result<Self>
    where
        S: AsRef<str>,
    {
        let address =
            util::parse_address(address).context("failed to parse address for Snowtrace source")?;
        Ok(Source::Snowtrace(address))
    }

    /// Creates an Etherscan source from an address string.
    pub fn npm<S>(package_path: S) -> Self
    where
        S: Into<String>,
    {
        Source::Npm(package_path.into())
    }

    /// Retrieves the source JSON of the artifact this will either read the JSON
    /// from the file system or retrieve a contract ABI from the network
    /// depending on the source type.
    pub fn get(&self) -> Result<String> {
        cfg_if! {
             if #[cfg(target_arch = "wasm32")] {
                match self {
                    Source::Local(path) => get_local_contract(path),
                    Source::Http(_) =>   panic!("Http abi location are not supported for wasm"),
                    Source::Etherscan(_) => panic!("Etherscan abi location are not supported for wasm"),
                    Source::Polygonscan(_) => panic!("Polygonscan abi location are not supported for wasm"),
                    Source::Snowtrace(_) => panic!("Snowtrace abi location are not supported for wasm"),
                    Source::Npm(_) => panic!("npm abi location are not supported for wasm"),
                    Source::String(abi) => Ok(abi.clone()),
                }
             } else {
                match self {
                    Source::Local(path) => get_local_contract(path),
                    Source::Http(url) => get_http_contract(url),
                    Source::Etherscan(address) => get_etherscan_contract(*address, "etherscan.io"),
                    Source::Polygonscan(address) => get_etherscan_contract(*address, "polygonscan.com"),
                    Source::Snowtrace(address) => get_etherscan_contract(*address, "snowtrace.io"),
                    Source::Npm(package) => get_npm_contract(package),
                    Source::String(abi) => Ok(abi.clone()),
                }
            }
        }
    }
}

impl FromStr for Source {
    type Err = Error;

    fn from_str(s: &str) -> Result<Self> {
        Source::parse(s)
    }
}

/// Reads an artifact JSON file from the local filesystem.
///
/// The given path can be relative or absolute and can contain env vars like
///  `"$CARGO_MANIFEST_DIR/contracts/a.json"`
/// If the path is relative after all env vars have been resolved then we assume the root is either
/// `CARGO_MANIFEST_DIR` or the current working directory.
fn get_local_contract(path: impl AsRef<str>) -> Result<String> {
    let path = resolve_path(path.as_ref())?;
    let path = if path.is_relative() {
        let manifest_path = env::var("CARGO_MANIFEST_DIR")?;
        let root = Path::new(&manifest_path);
        let mut contract_path = root.join(&path);
        if !contract_path.exists() {
            contract_path = dunce::canonicalize(&path)?;
        }
        if !contract_path.exists() {
            eyre::bail!("Unable to find local contract \"{}\"", path.display())
        }
        contract_path
    } else {
        path
    };

    let json = fs::read_to_string(&path)
        .context(format!("failed to read artifact JSON file with path {}", &path.display()))?;
    Ok(json)
}

/// Retrieves a Truffle artifact or ABI from an HTTP URL.
#[cfg(not(target_arch = "wasm32"))]
fn get_http_contract(url: &Url) -> Result<String> {
    let json = util::http_get(url.as_str())
        .with_context(|| format!("failed to retrieve JSON from {}", url))?;
    Ok(json)
}

/// Retrieves a contract ABI from the Etherscan HTTP API and wraps it in an
/// artifact JSON for compatibility with the code generation facilities.
#[cfg(not(target_arch = "wasm32"))]
fn get_etherscan_contract(address: Address, domain: &str) -> Result<String> {
    // NOTE: We do not retrieve the bytecode since deploying contracts with the
    //   same bytecode is unreliable as the libraries have already linked and
    //   probably don't reference anything when deploying on other networks.
    let api_key = {
        let key_res = match domain {
            "etherscan.io" => env::var("ETHERSCAN_API_KEY").ok(),
            "polygonscan.com" => env::var("POLYGONSCAN_API_KEY").ok(),
            "snowtrace.io" => env::var("SNOWTRACE_API_KEY").ok(),
            _ => None,
        };
        key_res.map(|key| format!("&apikey={}", key)).unwrap_or_default()
    };

    let abi_url = format!(
        "http://api.{}/api?module=contract&action=getabi&address={:?}&format=raw{}",
        domain, address, api_key,
    );
    let abi =
        util::http_get(&abi_url).context(format!("failed to retrieve ABI from {}", domain))?;

    if abi.starts_with("Contract source code not verified") {
        eyre::bail!("Contract source code not verified: {:?}", address);
    }

    Ok(abi)
}

/// Retrieves a Truffle artifact or ABI from an npm package through `unpkg.io`.
#[cfg(not(target_arch = "wasm32"))]
fn get_npm_contract(package: &str) -> Result<String> {
    let unpkg_url = format!("https://unpkg.io/{}", package);
    let json = util::http_get(&unpkg_url)
        .with_context(|| format!("failed to retrieve JSON from for npm package {}", package))?;

    Ok(json)
}

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

    #[test]
    fn parse_source() {
        let root = "/rooted";
        for (url, expected) in &[
            ("relative/Contract.json", Source::local("/rooted/relative/Contract.json")),
            ("/absolute/Contract.json", Source::local("/absolute/Contract.json")),
            (
                "https://my.domain.eth/path/to/Contract.json",
                Source::http("https://my.domain.eth/path/to/Contract.json").unwrap(),
            ),
            (
                "etherscan:0x0001020304050607080910111213141516171819",
                Source::etherscan("0x0001020304050607080910111213141516171819").unwrap(),
            ),
            (
                "polygonscan:0x0001020304050607080910111213141516171819",
                Source::polygonscan("0x0001020304050607080910111213141516171819").unwrap(),
            ),
            (
                "snowtrace:0x0001020304050607080910111213141516171819",
                Source::snowtrace("0x0001020304050607080910111213141516171819").unwrap(),
            ),
            (
                "https://etherscan.io/address/0x0001020304050607080910111213141516171819",
                Source::etherscan("0x0001020304050607080910111213141516171819").unwrap(),
            ),
            (
                "https://polygonscan.com/address/0x0001020304050607080910111213141516171819",
                Source::polygonscan("0x0001020304050607080910111213141516171819").unwrap(),
            ),
            (
                "https://snowtrace.io/address/0x0001020304050607080910111213141516171819",
                Source::snowtrace("0x0001020304050607080910111213141516171819").unwrap(),
            ),
            (
                "npm:@openzeppelin/contracts@2.5.0/build/contracts/IERC20.json",
                Source::npm("@openzeppelin/contracts@2.5.0/build/contracts/IERC20.json"),
            ),
        ] {
            let source = Source::with_root(root, url).unwrap();
            assert_eq!(source, *expected);
        }

        let src = r#"[{"constant":true,"inputs":[],"name":"name","outputs":[{"name":"name","type":"string"}],"payable":false,"type":"function"},{"constant":true,"inputs":[],"name":"symbol","outputs":[{"name":"symbol","type":"string"}],"payable":false,"type":"function"},{"constant":true,"inputs":[],"name":"decimals","outputs":[{"name":"decimals","type":"uint8"}],"payable":false,"type":"function"},{"constant":false,"inputs":[{"name":"spender","type":"address"},{"name":"value","type":"uint256"}],"name":"approve","outputs":[{"name":"success","type":"bool"}],"payable":false,"type":"function"},{"constant":true,"inputs":[],"name":"totalSupply","outputs":[{"name":"totalSupply","type":"uint256"}],"payable":false,"type":"function"},{"constant":false,"inputs":[{"name":"from","type":"address"},{"name":"to","type":"address"},{"name":"value","type":"uint256"}],"name":"transferFrom","outputs":[{"name":"success","type":"bool"}],"payable":false,"type":"function"},{"constant":true,"inputs":[{"name":"who","type":"address"}],"name":"balanceOf","outputs":[{"name":"balance","type":"uint256"}],"payable":false,"type":"function"},{"constant":false,"inputs":[{"name":"to","type":"address"},{"name":"value","type":"uint256"}],"name":"transfer","outputs":[{"name":"success","type":"bool"}],"payable":false,"type":"function"},{"constant":true,"inputs":[{"name":"owner","type":"address"},{"name":"spender","type":"address"}],"name":"allowance","outputs":[{"name":"remaining","type":"uint256"}],"payable":false,"type":"function"},{"anonymous":false,"inputs":[{"indexed":true,"name":"owner","type":"address"},{"indexed":true,"name":"spender","type":"address"},{"indexed":false,"name":"value","type":"uint256"}],"name":"Approval","type":"event"},{"anonymous":false,"inputs":[{"indexed":true,"name":"from","type":"address"},{"indexed":true,"name":"to","type":"address"},{"indexed":false,"name":"value","type":"uint256"}],"name":"Transfer","type":"event"}]"#;
        let parsed = Source::parse(src).unwrap();
        assert_eq!(parsed, Source::String(src.to_owned()));

        let hardhat_src = format!(
            r#"{{"_format": "hh-sol-artifact-1", "contractName": "Verifier", "sourceName": "contracts/verifier.sol", "abi": {}, "bytecode": "0x", "deployedBytecode": "0x", "linkReferences": {{}}, "deployedLinkReferences": {{}}}}"#,
            src,
        );
        let hardhat_parsed = Source::parse(&hardhat_src).unwrap();
        assert_eq!(hardhat_parsed, Source::String(hardhat_src));
    }

    #[test]
    #[ignore]
    fn get_etherscan_contract() {
        let source = Source::etherscan("0x6b175474e89094c44da98b954eedeac495271d0f").unwrap();
        let _dai = source.get().unwrap();
    }
}