use ethers_core::types::Address;

use anyhow::{anyhow, Result};
use cargo_metadata::{CargoOpt, DependencyKind, Metadata, MetadataCommand};
use inflector::Inflector;
use once_cell::sync::Lazy;
use proc_macro2::{Ident, Literal, Span, TokenStream};
use quote::quote;
use reqwest::Client;
use syn::{Ident as SynIdent, Path};

/// See `determine_ethers_crates`
///
/// This ensures that the `MetadataCommand` is only run once
static ETHERS_CRATES: Lazy<(&'static str, &'static str)> = Lazy::new(determine_ethers_crates);

/// Convenience function to turn the `ethers_core` name in `ETHERS_CRATE` into a `Path`
pub fn ethers_core_crate() -> Path {
    syn::parse_str(ETHERS_CRATES.0).expect("valid path; qed")
}
/// Convenience function to turn the `ethers_contract` name in `ETHERS_CRATE` into an `Path`
pub fn ethers_contract_crate() -> Path {
    syn::parse_str(ETHERS_CRATES.1).expect("valid path; qed")
}

/// The crates name to use when deriving macros: (`core`, `contract`)
///
/// We try to determine which crate ident to use based on the dependencies of
/// the project in which the macro is used. This is useful because the macros,
/// like `EthEvent` are provided by the `ethers-contract` crate which depends on
/// `ethers_core`. Most commonly `ethers` will be used as dependency which
/// reexports all the different crates, essentially `ethers::core` is
/// `ethers_core` So depending on the dependency used `ethers` ors `ethers_core
/// | ethers_contract`, we need to use the fitting crate ident when expand the
/// macros This will attempt to parse the current `Cargo.toml` and check the
/// ethers related dependencies.
pub fn determine_ethers_crates() -> (&'static str, &'static str) {
    MetadataCommand::new()
        .manifest_path(&format!(
            "{}/Cargo.toml",
            std::env::var("CARGO_MANIFEST_DIR").expect("No Manifest found")
        ))
        .exec()
        .ok()
        .and_then(|metadata| {
            metadata.root_package().and_then(|pkg| {
                pkg.dependencies
                    .iter()
                    .filter(|dep| dep.kind == DependencyKind::Normal)
                    .find_map(|dep| {
                        (dep.name == "ethers").then(|| ("ethers::core", "ethers::contract"))
                    })
            })
        })
        .unwrap_or(("ethers_core", "ethers_contract"))
}

/// Expands a identifier string into an token.
pub fn ident(name: &str) -> Ident {
    Ident::new(name, Span::call_site())
}

/// Expands an identifier string into a token and appending `_` if the
/// identifier is for a reserved keyword.
///
/// Parsing keywords like `self` can fail, in this case we add an underscore.
pub fn safe_ident(name: &str) -> Ident {
    syn::parse_str::<SynIdent>(name).unwrap_or_else(|_| ident(&format!("{}_", name)))
}

/// Expands a positional identifier string that may be empty.
///
/// Note that this expands the parameter name with `safe_ident`, meaning that
/// identifiers that are reserved keywords get `_` appended to them.
pub fn expand_input_name(index: usize, name: &str) -> TokenStream {
    let name_str = match name {
        "" => format!("p{}", index),
        n => n.to_snake_case(),
    };
    let name = safe_ident(&name_str);

    quote! { #name }
}

/// Expands a doc string into an attribute token stream.
pub fn expand_doc(s: &str) -> TokenStream {
    let doc = Literal::string(s);
    quote! {
        #[doc = #doc]
    }
}

/// Parses the given address string
pub fn parse_address<S>(address_str: S) -> Result<Address>
where
    S: AsRef<str>,
{
    let address_str = address_str.as_ref();
    if !address_str.starts_with("0x") {
        return Err(anyhow!("address must start with '0x'"));
    }
    Ok(address_str[2..].parse()?)
}

/// Perform an HTTP GET request and return the contents of the response.
pub fn http_get(url: &str) -> Result<String> {
    Ok(reqwest::blocking::get(url)?.text()?)
}

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

    #[test]
    fn input_name_to_ident_empty() {
        assert_quote!(expand_input_name(0, ""), { p0 });
    }

    #[test]
    fn input_name_to_ident_keyword() {
        assert_quote!(expand_input_name(0, "self"), { self_ });
    }

    #[test]
    fn input_name_to_ident_snake_case() {
        assert_quote!(expand_input_name(0, "CamelCase1"), { camel_case_1 });
    }

    #[test]
    fn parse_address_missing_prefix() {
        if parse_address("0000000000000000000000000000000000000000").is_ok() {
            panic!("parsing address not starting with 0x should fail");
        }
    }

    #[test]
    fn parse_address_address_too_short() {
        if parse_address("0x00000000000000").is_ok() {
            panic!("parsing address not starting with 0x should fail");
        }
    }

    #[test]
    fn parse_address_ok() {
        let expected = Address::from([
            0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19,
        ]);
        assert_eq!(
            parse_address("0x000102030405060708090a0b0c0d0e0f10111213").unwrap(),
            expected
        );
    }
}