use anyhow::Result;
use clap::Args;
use std::path::PathBuf;

#[derive(Args, Debug)]
#[command(
    about = "Output random DIDs sampled from the index",
    alias = "rand",
    long_about = "Sample random DIDs from the repository for testing, analysis, or statistical
purposes. Uses the DID index to efficiently select random identifiers without
scanning all bundles.

By default outputs DIDs as newline-delimited text, one per line. Use --json
to output as a JSON array instead. The --seed flag enables deterministic
sampling for reproducible results across runs.

This command is particularly useful for generating test datasets, performing
statistical analysis on DID distributions, or creating random samples for
benchmarking and performance testing.",
    help_template = crate::clap_help!(
        examples: "  # Sample 10 random DIDs (default)\n  \
                   {bin} random\n\n  \
                   # Sample specific number\n  \
                   {bin} random --count 50\n\n  \
                   # Deterministic sampling with seed\n  \
                   {bin} random --count 20 --seed 12345\n\n  \
                   # Output as JSON array\n  \
                   {bin} random --count 10 --json\n\n  \
                   # Using short flag\n  \
                   {bin} random -n 5"
    )
)]
pub struct RandomCommand {
    /// Number of random DIDs to output
    #[arg(short = 'n', long = "count", default_value = "10")]
    pub count: usize,

    /// Optional deterministic seed
    #[arg(long)]
    pub seed: Option<u64>,

    /// Emit JSON array instead of newline-delimited text
    #[arg(long)]
    pub json: bool,
}

pub fn run(cmd: RandomCommand, dir: PathBuf) -> Result<()> {
    let manager = super::utils::create_manager(dir, false, false, false)?;
    let count = cmd.count.max(1);
    let dids = manager.sample_random_dids(count, cmd.seed)?;

    if cmd.json {
        println!("{}", serde_json::to_string_pretty(&dids)?);
    } else {
        for did in dids {
            println!("{}", did);
        }
    }

    Ok(())
}