//! Utility functions

use std::path::{Component, Path, PathBuf};

use crate::error::SolcError;
use once_cell::sync::Lazy;
use regex::Regex;
use semver::Version;
use tiny_keccak::{Hasher, Keccak};
use walkdir::WalkDir;

/// A regex that matches the import path and identifier of a solidity import
/// statement with the named groups "path", "id".
pub static RE_SOL_IMPORT: Lazy<Regex> = Lazy::new(|| {
    // Adapted from https://github.com/nomiclabs/hardhat/blob/cced766c65b25d3d0beb39ef847246ac9618bdd9/packages/hardhat-core/src/internal/solidity/parse.ts#L100
    Regex::new(r#"import\s+(?:(?:"(?P<p1>[^;]*)"|'([^;]*)')(?:;|\s+as\s+(?P<id>[^;]*);)|.+from\s+(?:"(?P<p2>.*)"|'(?P<p3>.*)');)"#).unwrap()
});

/// A regex that matches the version part of a solidity pragma
/// as follows: `pragma solidity ^0.5.2;` => `^0.5.2`
/// statement with the named groups "path", "id".
// Adapted from https://github.com/nomiclabs/hardhat/blob/cced766c65b25d3d0beb39ef847246ac9618bdd9/packages/hardhat-core/src/internal/solidity/parse.ts#L119
pub static RE_SOL_PRAGMA_VERSION: Lazy<Regex> =
    Lazy::new(|| Regex::new(r"pragma\s+solidity\s+(?P<version>.+?);").unwrap());

/// Returns all path parts from any solidity import statement in a string,
/// `import "./contracts/Contract.sol";` -> `"./contracts/Contract.sol"`.
///
/// See also https://docs.soliditylang.org/en/v0.8.9/grammar.html
pub fn find_import_paths(contract: &str) -> Vec<&str> {
    RE_SOL_IMPORT
        .captures_iter(contract)
        .filter_map(|cap| cap.name("p1").or_else(|| cap.name("p2")).or_else(|| cap.name("p3")))
        .map(|m| m.as_str())
        .collect()
}

/// Returns the solidity version pragma from the given input:
/// `pragma solidity ^0.5.2;` => `^0.5.2`
pub fn find_version_pragma(contract: &str) -> Option<&str> {
    RE_SOL_PRAGMA_VERSION.captures(contract)?.name("version").map(|m| m.as_str())
}

/// Returns a list of absolute paths to all the solidity files under the root
///
/// NOTE: this does not resolve imports from other locations
///
/// # Example
///
/// ```no_run
/// use ethers_solc::utils;
/// let sources = utils::source_files("./contracts");
/// ```
pub fn source_files(root: impl AsRef<Path>) -> Vec<PathBuf> {
    WalkDir::new(root)
        .into_iter()
        .filter_map(Result::ok)
        .filter(|e| e.file_type().is_file())
        .filter(|e| e.path().extension().map(|ext| ext == "sol").unwrap_or_default())
        .map(|e| e.path().into())
        .collect()
}

/// Returns the source name for the given source path, the ancestors of the root path
/// `/Users/project/sources/contract.sol` -> `sources/contracts.sol`
pub fn source_name(source: &Path, root: impl AsRef<Path>) -> &Path {
    source.strip_prefix(root.as_ref()).unwrap_or(source)
}

/// Attempts to determine if the given source is a local, relative import
pub fn is_local_source_name(libs: &[impl AsRef<Path>], source: impl AsRef<Path>) -> bool {
    resolve_library(libs, source).is_none()
}

/// Returns the path to the library if the source path is in fact determined to be a library path,
/// and it exists.
pub fn resolve_library(libs: &[impl AsRef<Path>], source: impl AsRef<Path>) -> Option<PathBuf> {
    let source = source.as_ref();
    let comp = source.components().next()?;
    match comp {
        Component::Normal(first_dir) => {
            // attempt to verify that the root component of this source exists under a library
            // folder
            for lib in libs {
                let lib = lib.as_ref();
                let contract = lib.join(source);
                if contract.exists() {
                    // contract exists in <lib>/<source>
                    return Some(contract)
                }
                // check for <lib>/<first_dir>/src/name.sol
                let contract = lib
                    .join(first_dir)
                    .join("src")
                    .join(source.strip_prefix(first_dir).expect("is first component"));
                if contract.exists() {
                    return Some(contract)
                }
            }
            None
        }
        Component::RootDir => Some(source.into()),
        _ => None,
    }
}

/// Reads the list of Solc versions that have been installed in the machine. The version list is
/// sorted in ascending order.
/// Checks for installed solc versions under the given path as
/// `<root>/<major.minor.path>`, (e.g.: `~/.svm/0.8.10`)
/// and returns them sorted in ascending order
pub fn installed_versions(root: impl AsRef<Path>) -> Result<Vec<Version>, SolcError> {
    let mut versions: Vec<_> = walkdir::WalkDir::new(root)
        .max_depth(1)
        .into_iter()
        .filter_map(std::result::Result::ok)
        .filter(|e| e.file_type().is_dir())
        .filter_map(|e: walkdir::DirEntry| {
            e.path().file_name().and_then(|v| Version::parse(v.to_string_lossy().as_ref()).ok())
        })
        .collect();
    versions.sort();
    Ok(versions)
}

/// Returns the 36 char (deprecated) fully qualified name placeholder
///
/// If the name is longer than 36 char, then the name gets truncated,
/// If the name is shorter than 36 char, then the name is filled with trailing `_`
pub fn library_fully_qualified_placeholder(name: impl AsRef<str>) -> String {
    name.as_ref().chars().chain(std::iter::repeat('_')).take(36).collect()
}

/// Returns the library hash placeholder as `$hex(library_hash(name))$`
pub fn library_hash_placeholder(name: impl AsRef<[u8]>) -> String {
    let hash = library_hash(name);
    let placeholder = hex::encode(hash);
    format!("${}$", placeholder)
}

/// Returns the library placeholder for the given name
/// The placeholder is a 34 character prefix of the hex encoding of the keccak256 hash of the fully
/// qualified library name.
///
/// See also https://docs.soliditylang.org/en/develop/using-the-compiler.html#library-linking
pub fn library_hash(name: impl AsRef<[u8]>) -> [u8; 17] {
    let mut output = [0u8; 17];
    let mut hasher = Keccak::v256();
    hasher.update(name.as_ref());
    hasher.finalize(&mut output);
    output
}

/// Find the common ancestor, if any, between the given paths
///
/// # Example
///
/// ```rust
/// use std::path::{PathBuf, Path};
///
/// # fn main() {
/// use ethers_solc::utils::common_ancestor_all;
/// let baz = Path::new("/foo/bar/baz");
/// let bar = Path::new("/foo/bar/bar");
/// let foo = Path::new("/foo/bar/foo");
/// let common = common_ancestor_all(vec![baz, bar, foo]).unwrap();
/// assert_eq!(common, Path::new("/foo/bar").to_path_buf());
/// # }
/// ```
pub fn common_ancestor_all<I, P>(paths: I) -> Option<PathBuf>
where
    I: IntoIterator<Item = P>,
    P: AsRef<Path>,
{
    let mut iter = paths.into_iter();
    let mut ret = iter.next()?.as_ref().to_path_buf();
    for path in iter {
        if let Some(r) = common_ancestor(ret, path.as_ref()) {
            ret = r;
        } else {
            return None
        }
    }
    Some(ret)
}

/// Finds the common ancestor of both paths
///
/// # Example
///
/// ```rust
/// use std::path::{PathBuf, Path};
///
/// # fn main() {
/// use ethers_solc::utils::common_ancestor;
/// let foo = Path::new("/foo/bar/foo");
/// let bar = Path::new("/foo/bar/bar");
/// let ancestor = common_ancestor(foo, bar).unwrap();
/// assert_eq!(ancestor, Path::new("/foo/bar").to_path_buf());
/// # }
/// ```
pub fn common_ancestor(a: impl AsRef<Path>, b: impl AsRef<Path>) -> Option<PathBuf> {
    let a = a.as_ref().components();
    let b = b.as_ref().components();
    let mut ret = PathBuf::new();
    let mut found = false;
    for (c1, c2) in a.zip(b) {
        if c1 == c2 {
            ret.push(c1);
            found = true;
        } else {
            break
        }
    }
    if found {
        Some(ret)
    } else {
        None
    }
}

#[cfg(test)]
mod tests {
    use super::*;
    use std::{
        collections::HashSet,
        fs::{create_dir_all, File},
    };

    use tempdir::TempDir;

    #[test]
    fn can_determine_local_paths() {
        assert!(is_local_source_name(&[""], "./local/contract.sol"));
        assert!(is_local_source_name(&[""], "../local/contract.sol"));
        assert!(!is_local_source_name(&[""], "/ds-test/test.sol"));

        let tmp_dir = TempDir::new("contracts").unwrap();
        let dir = tmp_dir.path().join("ds-test");
        create_dir_all(&dir).unwrap();
        File::create(dir.join("test.sol")).unwrap();

        assert!(!is_local_source_name(&[tmp_dir.path()], "ds-test/test.sol"));
    }

    #[test]
    fn can_find_solidity_sources() {
        let tmp_dir = TempDir::new("contracts").unwrap();

        let file_a = tmp_dir.path().join("a.sol");
        let file_b = tmp_dir.path().join("a.sol");
        let nested = tmp_dir.path().join("nested");
        let file_c = nested.join("c.sol");
        let nested_deep = nested.join("deep");
        let file_d = nested_deep.join("d.sol");
        File::create(&file_a).unwrap();
        File::create(&file_b).unwrap();
        create_dir_all(nested_deep).unwrap();
        File::create(&file_c).unwrap();
        File::create(&file_d).unwrap();

        let files: HashSet<_> = source_files(tmp_dir.path()).into_iter().collect();
        let expected: HashSet<_> = [file_a, file_b, file_c, file_d].into();
        assert_eq!(files, expected);
    }

    #[test]
    fn can_find_import_paths() {
        let s = r##"//SPDX-License-Identifier: Unlicense
pragma solidity ^0.8.0;
import "hardhat/console.sol";
import "../contract/Contract.sol";
import { T } from "../Test.sol";
import { T } from '../Test2.sol';
"##;
        assert_eq!(
            vec!["hardhat/console.sol", "../contract/Contract.sol", "../Test.sol", "../Test2.sol"],
            find_import_paths(s)
        );
    }
    #[test]
    fn can_find_version() {
        let s = r##"//SPDX-License-Identifier: Unlicense
pragma solidity ^0.8.0;
"##;
        assert_eq!(Some("^0.8.0"), find_version_pragma(s));
    }

    #[test]
    fn can_find_ancestor() {
        let a = Path::new("/foo/bar/bar/test.txt");
        let b = Path::new("/foo/bar/foo/example/constract.sol");
        let expected = Path::new("/foo/bar");
        assert_eq!(common_ancestor(&a, &b).unwrap(), expected.to_path_buf())
    }

    #[test]
    fn no_common_ancestor_path() {
        let a = Path::new("/foo/bar");
        let b = Path::new("./bar/foo");
        assert!(common_ancestor(a, b).is_none());
    }

    #[test]
    fn can_find_all_ancestor() {
        let a = Path::new("/foo/bar/foo/example.txt");
        let b = Path::new("/foo/bar/foo/test.txt");
        let c = Path::new("/foo/bar/bar/foo/bar");
        let expected = Path::new("/foo/bar");
        let paths = vec![a, b, c];
        assert_eq!(common_ancestor_all(paths).unwrap(), expected.to_path_buf())
    }
}