use std::{collections::HashMap, fmt::Debug};

use anyhow::{anyhow, Result};
use graphql_client::{reqwest::post_graphql, GraphQLQuery};
use reqwest::{
    header::{HeaderMap, HeaderValue},
    Client,
};
use serde::Deserialize;
use tracing::instrument;

const ENDPOINT: &str = "https://api.github.com/graphql";

type GitObjectID = String;

#[derive(GraphQLQuery)]
#[graphql(
    query_path = "src/github/get_commit_sha.graphql",
    schema_path = "src/github/schema_gh.graphql",
    response_derives = "Debug"
)]
pub(crate) struct LatestCommit;

#[derive(Deserialize, Clone)]
struct GhHost {
    // user: String,
    oauth_token: String,
    // git_protocoll: String,
}

#[instrument]
pub(crate) async fn get_latest_commit(owner: &str, repo: &str, branch: &str) -> Result<String> {
    use latest_commit::LatestCommitRepositoryRefTarget::*;
    use latest_commit::LatestCommitRepositoryRefTargetOnCommit;

    let auth = get_gh_creds();

    let variables = latest_commit::Variables {
        repo: repo.into(),
        owner: owner.into(),
        branch: branch.into(),
    };

    let mut headers = HeaderMap::new();
    headers.insert(
        "Authorization",
        HeaderValue::from_str(&format!("bearer {}", auth.await?.oauth_token))?,
    );

    let client = Client::builder()
        .user_agent("nobbz switcher/0.0")
        .default_headers(headers)
        .build()?;

    let target = post_graphql::<LatestCommit, _>(&client, ENDPOINT, variables)
        .await?
        .data
        .ok_or_else(|| anyhow!("missing in response: data"))?
        .repository
        .ok_or_else(|| anyhow!("missing in response: repository"))?
        .ref_
        .ok_or_else(|| anyhow!("missing in response: ref"))?
        .target
        .ok_or_else(|| anyhow!("missing in response: target"))?;

    if let Commit(LatestCommitRepositoryRefTargetOnCommit { oid }) = target {
        Ok(oid)
    } else {
        Err(anyhow!("Not a commit: {:?}", target))
    }
}

#[instrument]
async fn get_gh_creds() -> Result<GhHost> {
    let home = std::env::var("HOME")?;
    let path = std::path::Path::new(&home).join(".config/gh/hosts.yml");
    let f = tokio::fs::File::open(path).await?;
    let d: HashMap<String, GhHost> = serde_yaml::from_reader(f.into_std().await)?;

    d.get("github.com")
        .cloned()
        .ok_or_else(|| anyhow!("Host not configured: github.com"))
}