hive-forge: rewrite bash CLI helper as a rust binary (closes #280)

hive-forge/src/body.rs

@@ -0,0 +1,56 @@
+//! Body-input resolution shared by every verb that posts a body.
+//! Matches the bash `resolve_body` helper (#382): exactly one source
+//! between `--body`, `--body-file`, and piped stdin. Passing both
+//! `--body` and `--body-file` is a clear error.
+
+use std::io::{IsTerminal, Read};
+
+use anyhow::{Context, Result, bail};
+
+/// Resolve the body to send, given the user's explicit flags and the
+/// current stdin state. Returns `None` when none of the sources are
+/// available (the caller decides whether that's allowed — e.g.
+/// `issue-edit` treats absent body as "leave unchanged", while
+/// `comment` treats absent body as a hard error).
+pub fn resolve(body: Option<&str>, file: Option<&str>) -> Result<Option<String>> {
+    if body.is_some() && file.is_some() {
+        bail!("hive-forge: --body and --body-file are mutually exclusive");
+    }
+    if let Some(b) = body {
+        return Ok(Some(b.to_owned()));
+    }
+    if let Some(path) = file {
+        if path == "-" {
+            return Ok(Some(read_stdin().context("read stdin for --body-file -")?));
+        }
+        let s = std::fs::read_to_string(path)
+            .with_context(|| format!("read --body-file {path}"))?;
+        return Ok(Some(s));
+    }
+    if !std::io::stdin().is_terminal() {
+        return Ok(Some(read_stdin().context("read piped stdin")?));
+    }
+    Ok(None)
+}
+
+/// Resolve, then require a non-empty result (whitespace-trimmed).
+/// Used by `comment` / `comment-edit` which refuse to post empty
+/// bodies.
+pub fn resolve_required(body: Option<&str>, file: Option<&str>, verb: &str) -> Result<String> {
+    let resolved = resolve(body, file)?;
+    let Some(s) = resolved else {
+        bail!(
+            "hive-forge {verb}: no body — pass --body <text>, --body-file <path>, or pipe via stdin"
+        );
+    };
+    if s.trim().is_empty() {
+        bail!("hive-forge {verb}: refusing to post empty body");
+    }
+    Ok(s)
+}
+
+fn read_stdin() -> std::io::Result<String> {
+    let mut s = String::new();
+    std::io::stdin().read_to_string(&mut s)?;
+    Ok(s)
+}