//! `pr-commits <number> [repo]` — list a PR's commits as JSON
//! (sha, message, author date, author login), paginated.
//!
//! The forge stores a PR's commits against its branch ref, so this
//! returns them even for a PR whose shas were rewritten by a rebase
//! merge. The commit message and author date survive a rebase
//! unchanged, so a caller can match these rows against the linear
//! `main` history to recover the merged-final commits when the PR's
//! recorded shas no longer resolve.

use anyhow::Result;
use clap::Args as ClapArgs;
use forgejo_api::structs::{Commit, RepoGetPullRequestCommitsQuery};
use serde_json::json;

use crate::client::{Client, index};
use crate::verbs::{print_json, rfc3339};

/// Page cap for the commit list. Forgejo serves up to 50 commits per
/// page; 40 pages (2000 commits) is far beyond any real PR.
const MAX_PAGES: u32 = 40;

/// Page size on the commit list endpoint (Forgejo's cap).
const PAGE_SIZE: u32 = 50;

#[derive(ClapArgs)]
pub struct Args {
    /// PR number.
    number: u64,
}

pub fn run(client: &Client, args: Args) -> Result<()> {
    let (owner, name) = client.owner_repo()?;
    let idx = index(args.number)?;
    let mut commits: Vec<Commit> = Vec::new();
    for page in 1..=MAX_PAGES {
        let (_, batch) = client
            .api()
            .repo_get_pull_request_commits(
                owner,
                name,
                idx,
                RepoGetPullRequestCommitsQuery::default(),
            )
            .page(page)
            .page_size(PAGE_SIZE)
            .send()?;
        let short = batch.len() < PAGE_SIZE as usize;
        commits.extend(batch);
        if short {
            break;
        }
    }
    let trimmed: Vec<_> = commits
        .iter()
        .map(|c| {
            json!({
                "sha": c.sha,
                "message": c.commit.as_ref().and_then(|x| x.message.as_deref()),
                "author_date": rfc3339(c.commit.as_ref().and_then(|x| x.author.as_ref()).and_then(|a| a.date)),
                "author": c.author.as_ref().and_then(|u| u.login.as_deref()),
            })
        })
        .collect();
    print_json(&json!(trimmed))
}