// dep_tree.nyash — Build dependency info for a Nyash script (include + using/module)

static box DepTree {
  init { visited }

  // Public API: build tree for entry path
  build(entry_path) {
    me.visited = new MapBox()
    return me.node(entry_path)
  }

  // Read entire file as string via FileBox
  read_file(path) {
    local fb = new FileBox()
    local ok = fb.open(path, "r")
    if ok == false { return null }
    local content = fb.read()
    fb.close()
    return content
  }

  // Extract include paths from source: include "./path.nyash"
  extract_includes(src) {
    local out = new ArrayBox()
    if src == null { return out }
    local i = 0
    local n = src.length()
    loop(i < n) {
      local j = src.indexOf("include \"", i)
      if j < 0 { break }
      local k = j + 9 // after include "
      local q = src.indexOf("\"", k)
      if q < 0 { break }
      out.push(src.substring(k, q))
      i = q + 1
    }
    return out
  }

  // Extract using directives (script lines):
  //  using ns
  //  using ns as Alias
  //  using "path" as Name
  // and comment form: // @using ns[ as Alias]
  extract_usings(src) {
    local out = new ArrayBox()
    if src == null { return out }
    local lines = me.split_lines(src)
    local i = 0
    loop(i < lines.length()) {
      local line = lines.get(i).trim()
      local t = line
      if t.startsWith("// @using ") { t = t.substring(10, t.length()).trim() }
      else if t.startsWith("using ") { t = t.substring(6, t.length()).trim() }
      else { i = i + 1; continue }

      // optional trailing semicolon
      if t.endsWith(";") { t = t.substring(0, t.length()-1).trim() }

      local rec = new MapBox()
      // Split alias
      local as_pos = t.indexOf(" as ")
      local target = t
      local alias = null
      if as_pos >= 0 {
        target = t.substring(0, as_pos).trim()
        alias = t.substring(as_pos+4, t.length()).trim()
      }
      rec.set("target", target)
      if alias != null { rec.set("alias", alias) }
      // classify
      if target.startsWith("\"") || target.startsWith("./") || target.startsWith("/") || target.endsWith(".nyash") {
        rec.set("kind", "path")
        // strip quotes
        if target.startsWith("\"") { rec.set("target", target.substring(1, target.length()-1)) }
      } else {
        rec.set("kind", "ns")
      }
      out.push(rec)
      i = i + 1
    }
    return out
  }

  // Extract modules mapping from // @module ns=path
  extract_modules(src) {
    local out = new ArrayBox()
    if src != null {
      local lines = me.split_lines(src)
      local i = 0
      loop(i < lines.length()) {
        local line = lines.get(i).trim()
        if line.startsWith("// @module ") {
          local rest = line.substring(11, line.length()).trim()
          local eq = rest.indexOf("=")
          if eq > 0 {
            local ns = rest.substring(0, eq).trim()
            local path = rest.substring(eq+1, rest.length()).trim()
            path = me.strip_quotes(path)
            local m = new MapBox(); m.set("ns", ns); m.set("path", path); out.push(m)
          }
        }
        i = i + 1
      }
    }
    return out
  }

  // Build a node: { path, includes:[...], using:[...], modules:[...], children:[...] }
  node(path) {
    if me.visited.has(path) { return me.leaf(path) }
    me.visited.set(path, true)

    local m = new MapBox(); m.set("path", path)
    local src = me.read_file(path)
    if src == null { m.set("error", "read_fail"); me.ensure_arrays(m); return m }

    local base_dir = me.dirname(path)

    // includes
    local incs = me.extract_includes(src)
    m.set("includes", incs)
    // usings
    local us = me.extract_usings(src)
    m.set("using", us)
    // modules mapping (script-level)
    local mods = me.extract_modules(src)
    m.set("modules", mods)

    // children = includes + resolved using(path) + resolved using(ns via search paths)
    local children = new ArrayBox()
    // include children
    local i = 0
    loop(i < incs.length()) {
      local p = incs.get(i)
      local child_path = me.resolve_path(base_dir, p)
      children.push(me.node(child_path))
      i = i + 1
    }
    // using(path) children
    i = 0
    loop(i < us.length()) {
      local u = us.get(i)
      if u.get("kind") == "path" {
        local p = u.get("target")
        local child_path = me.resolve_path(base_dir, p)
        children.push(me.node(child_path))
      }
      i = i + 1
    }
    // using(ns) children resolved via search paths
    local search = me.default_using_paths()
    i = 0
    loop(i < us.length()) {
      local u = us.get(i)
      if u.get("kind") == "ns" {
        local ns = u.get("target")
        local rel = ns.replace(".", "/") + ".nyash"
        local found = me.search_in_paths(base_dir, search, rel)
        if found != null { children.push(me.node(found)) }
        else {
          // annotate unresolved
          u.set("unresolved", true)
          u.set("hint", rel)
        }
      }
      i = i + 1
    }

    m.set("children", children)
    return m
  }

  // Helpers
  ensure_arrays(m) { m.set("includes", new ArrayBox()); m.set("using", new ArrayBox()); m.set("modules", new ArrayBox()); m.set("children", new ArrayBox()) }

  default_using_paths() {
    // Best-effort defaults prioritized for selfhost
    local arr = new ArrayBox()
    arr.push("apps/selfhost"); arr.push("apps"); arr.push("lib"); arr.push(".")
    return arr
  }

  split_lines(src) {
    local out = new ArrayBox()
    local i = 0; local n = src.length(); local start = 0
    loop(i <= n) {
      if i == n || src.substring(i, i+1) == "\n" {
        out.push(src.substring(start, i))
        start = i + 1
      }
      i = i + 1
    }
    return out
  }

  strip_quotes(s) {
    if s == null { return null }
    if s.length() >= 2 && s.substring(0,1) == "\"" && s.substring(s.length()-1, s.length()) == "\"" {
      return s.substring(1, s.length()-1)
    }
    return s
  }

  dirname(path) {
    local pb = new PathBox();
    local d = pb.dirname(path)
    if d != null { return d }
    local i = path.lastIndexOf("/")
    if i < 0 { return "." }
    return path.substring(0, i)
  }

  resolve_path(base, rel) {
    if rel.indexOf("/") == 0 { return rel }
    if rel.startsWith("./") || rel.startsWith("../") {
      local pb = new PathBox();
      local j = pb.join(base, rel)
      if j != null { return j }
      return base + "/" + rel
    }
    return rel
  }

  search_in_paths(base, paths, rel) {
    // try relative to file first
    local pb = new PathBox();
    local j = pb.join(base, rel)
    if me.file_exists(j) { return j }
    // then search list
    local i = 0
    loop(i < paths.length()) {
      local p = paths.get(i)
      local cand = pb.join(p, rel)
      if me.file_exists(cand) { return cand }
      i = i + 1
    }
    return null
  }

  file_exists(path) {
    // Use FileBox.open in read mode as exists check
    local fb = new FileBox();
    local ok = fb.open(path, "r")
    if ok == false { return false }
    fb.close(); return true
  }

  leaf(path) {
    local m = new MapBox(); m.set("path", path); m.set("children", new ArrayBox()); m.set("note", "visited")
    return m
  }
}