//! `cargo run -p benilla-formats --example chain_report [--toc | <file-in-chain>…]` — which archive
//! the client will actually read a file from, and why.
//!
//! The question a realm update raises. The reference mounts `patch-?.MPQ` by case-folded name, so a
//! letter patch outranks a digit patch ([`benilla_formats::Chain`]'s `mount_order`), and an update
//! shipped as `patch-4`/`patch-5` lands *below* every `patch-A..Z` already on disk. One deviation
//! corrects part of that — an archive whose `FrameXML.toc` is a strict subset of another's is
//! demoted as a stale snapshot — but an archive carrying no toc at all is not a candidate for it,
//! so after an update this is the measurement that says whether the new files are the ones being
//! read. `chain_shadow` answers the same question from the archive's side.
//!
//! - no argument: the `FrameXML.toc` copies in priority order, which is the evidence the demotion
//!   keys on, plus the winner of a handful of files an update moves.
//! - `--toc`: every row of the realm's own interface manifest with the archive that wins it, and a
//!   tally per archive. This is the one to read after an update: a row won by a *months-old* letter
//!   patch is a file the realm replaced and the client is not reading.
//! - file names: the winner for each, as the client's backslash paths.
//! - `--cat <file>`: the **winning** copy's bytes on stdout, which is the copy the client reads.
//!   Reading a shipped file any other way — unzipping an archive by hand, or trusting a copy on
//!   disk — answers a different question than "what does the client see", and after an update
//!   those two answers diverge, which is the whole reason this example exists.
fn main() {
    let Some(data) = benilla_formats::wow_data() else {
        eprintln!("no install");
        std::process::exit(1);
    };
    println!("data: {}", data.display());
    let chain = benilla_formats::Chain::open(&data).expect("chain opens");
    let toc = "Interface\\FrameXML\\FrameXML.toc";
    let args: Vec<String> = std::env::args().skip(1).collect();

    if let Some(i) = args.iter().position(|a| a == "--cat") {
        let Some(name) = args.get(i + 1) else {
            eprintln!("--cat needs a file name");
            std::process::exit(2);
        };
        let name = name.replace('/', "\\");
        match chain.read(&name) {
            Ok(bytes) => {
                eprintln!(
                    "-- {name}: {} bytes, from {} --",
                    bytes.len(),
                    winner(&chain, &name)
                );
                use std::io::Write;
                std::io::stdout().write_all(&bytes).expect("stdout");
            }
            Err(e) => {
                eprintln!("{name}: not in the chain ({e})");
                std::process::exit(1);
            }
        }
        return;
    }

    if args.iter().any(|a| a == "--toc") {
        let bytes = chain.read(toc).expect("the realm has a FrameXML.toc");
        let rows: Vec<String> = String::from_utf8_lossy(&bytes)
            .lines()
            .map(|l| l.trim().trim_start_matches('\u{feff}').to_string())
            .filter(|l| !l.is_empty() && !l.starts_with('#'))
            .collect();
        println!(
            "\n-- the realm's {} interface rows, and who wins each --",
            rows.len()
        );
        let mut tally: std::collections::BTreeMap<String, usize> = Default::default();
        for row in &rows {
            let name = format!("Interface\\FrameXML\\{}", row.replace('/', "\\"));
            let who = winner(&chain, &name);
            *tally.entry(who.clone()).or_default() += 1;
            println!("  {:<22} {row}", who);
        }
        println!("\n-- tally --");
        for (who, n) in &tally {
            println!("  {who:<22} {n}");
        }
        return;
    }

    println!("\n-- FrameXML.toc copies, ascending priority (last wins) --");
    for (path, size) in chain.copies(toc) {
        println!("  {:<22} {size:>8} bytes", name_of(path));
    }

    let files: Vec<String> = if args.is_empty() {
        [
            toc,
            "Interface\\FrameXML\\GlobalStrings.lua",
            "Interface\\FrameXML\\Minimap.lua",
            "Interface\\FrameXML\\TargetFrame.lua",
            "Interface\\GlueXML\\GlueXML.toc",
            "DBFilesClient\\Spell.dbc",
            "DBFilesClient\\AreaTable.dbc",
            "DBFilesClient\\Map.dbc",
            "DBFilesClient\\CreatureDisplayInfo.dbc",
        ]
        .iter()
        .map(|s| (*s).to_string())
        .collect()
    } else {
        args
    };
    println!("\n-- winners --");
    for f in &files {
        println!(
            "  {f:<46} {:<22} ({} copies)",
            winner(&chain, f),
            chain.copies(f).len()
        );
    }
}

/// The archive the chain resolves `name` from, or `ABSENT`.
fn winner(chain: &benilla_formats::Chain, name: &str) -> String {
    chain
        .find_file_archive(name)
        .map(|p| name_of(p).to_string())
        .unwrap_or_else(|| "ABSENT".to_string())
}

fn name_of(p: &std::path::Path) -> &str {
    p.file_name().and_then(|n| n.to_str()).unwrap_or("?")
}