use crate::db::{self, ChannelRole, NewUserParams};

use anyhow::Context;
use db::Database;
use serde::{de::DeserializeOwned, Deserialize};
use std::{fmt::Write, fs, path::Path};

use crate::Config;

#[derive(Debug, Deserialize)]
struct GitHubUser {
    id: i32,
    login: String,
    email: Option<String>,
}

#[derive(Deserialize)]
struct SeedConfig {
    // Which users to create as admins.
    admins: Vec<String>,
    // Which channels to create (all admins are invited to all channels)
    channels: Vec<String>,
    // Number of random users to create from the Github API
    number_of_users: Option<usize>,
}

pub async fn seed(config: &Config, db: &Database, force: bool) -> anyhow::Result<()> {
    let client = reqwest::Client::new();

    if !db.get_all_users(0, 1).await?.is_empty() && !force {
        return Ok(());
    }

    let seed_path = config
        .seed_path
        .as_ref()
        .context("called seed with no SEED_PATH")?;

    let seed_config = load_admins(seed_path)
        .context(format!("failed to load {}", seed_path.to_string_lossy()))?;

    let mut first_user = None;
    let mut others = vec![];

    for admin_login in seed_config.admins {
        let user = fetch_github::<GitHubUser>(
            &client,
            &format!("https://api.github.com/users/{admin_login}"),
        )
        .await;
        let user = db
            .create_user(
                &user.email.unwrap_or(format!("{admin_login}@example.com")),
                true,
                NewUserParams {
                    github_login: user.login,
                    github_user_id: user.id,
                },
            )
            .await
            .context("failed to create admin user")?;
        if first_user.is_none() {
            first_user = Some(user.user_id);
        } else {
            others.push(user.user_id)
        }
    }

    for channel in seed_config.channels {
        let (channel, _) = db
            .create_channel(&channel, None, first_user.unwrap())
            .await
            .context("failed to create channel")?;

        for user_id in &others {
            db.invite_channel_member(
                channel.id,
                *user_id,
                first_user.unwrap(),
                ChannelRole::Admin,
            )
            .await
            .context("failed to add user to channel")?;
        }
    }

    if let Some(number_of_users) = seed_config.number_of_users {
        // Fetch 100 other random users from GitHub and insert them into the database
        // (for testing autocompleters, etc.)
        let mut user_count = db
            .get_all_users(0, 200)
            .await
            .expect("failed to load users from db")
            .len();
        let mut last_user_id = None;
        while user_count < number_of_users {
            let mut uri = "https://api.github.com/users?per_page=100".to_string();
            if let Some(last_user_id) = last_user_id {
                write!(&mut uri, "&since={}", last_user_id).unwrap();
            }
            let users = fetch_github::<Vec<GitHubUser>>(&client, &uri).await;

            for github_user in users {
                last_user_id = Some(github_user.id);
                user_count += 1;
                db.get_or_create_user_by_github_account(
                    &github_user.login,
                    Some(github_user.id),
                    github_user.email.as_deref(),
                    None,
                )
                .await
                .expect("failed to insert user");
            }
        }
    }

    Ok(())
}

fn load_admins(path: impl AsRef<Path>) -> anyhow::Result<SeedConfig> {
    let file_content = fs::read_to_string(path)?;
    Ok(serde_json::from_str(&file_content)?)
}

async fn fetch_github<T: DeserializeOwned>(client: &reqwest::Client, url: &str) -> T {
    let response = client
        .get(url)
        .header("user-agent", "zed")
        .send()
        .await
        .unwrap_or_else(|_| panic!("failed to fetch '{}'", url));
    response
        .json()
        .await
        .unwrap_or_else(|_| panic!("failed to deserialize github user from '{}'", url))
}