# Builds the home-files tree `homeModules.default` produces under several
# operator configurations and asserts on the skills each one places.
{
  pkgs,
  home-manager,
  module,
  mkSkill,
}:
let
  inherit (pkgs) lib;

  # A sample skill built through the flake's own `mkSkill`, so it carries the
  # `skillName` passthru the module reads to place it.
  mkSampleSkill =
    name:
    mkSkill {
      inherit pkgs name;
      src = pkgs.runCommandLocal "${name}-src" { } ''
        mkdir -p "$out"
        printf '%s\n' "sample skill ${name}" > "$out/SKILL.md"
      '';
    };

  skillAlpha = mkSampleSkill "sample-alpha";
  skillBeta = mkSampleSkill "sample-beta";

  # A skill the operator declares as their own attribute-set entry, so the
  # attribute-set assertion can look for it beside the module's.
  operatorAttrSkill = pkgs.runCommandLocal "operator-attr-skill" { } ''
    mkdir -p "$out"
    printf '%s\n' "the operator's own attribute-set skill" > "$out/SKILL.md"
  '';

  # A whole directory of skills, one folder per skill, for the path form of the
  # operator's own `programs.claude-code.skills`.
  operatorSkillsDir = pkgs.runCommandLocal "operator-skills-dir" { } ''
    mkdir -p "$out/operator-dir-skill"
    printf '%s\n' "the operator's own whole-directory skill" \
      > "$out/operator-dir-skill/SKILL.md"
  '';

  # Evaluate the real module through home-manager's standalone entry point and
  # return the home-files tree it would link into $HOME.
  homeFiles =
    operatorConfig:
    (home-manager.lib.homeManagerConfiguration {
      inherit pkgs;
      modules = [
        module
        {
          home.username = "operator";
          home.homeDirectory = "/home/operator";
          home.stateVersion = "24.11";
        }
        operatorConfig
      ];
    }).config.home-files;

  # Two skills selected beside the operator's own attribute-set skill, with
  # Claude Code enabled.
  attrSetSkills = homeFiles {
    programs.claude-code.enable = true;
    programs.agents.skills = [
      skillAlpha
      skillBeta
    ];
    # A store path, not a bare derivation, so the value takes the option's path
    # branch rather than its attribute-set branch.
    programs.claude-code.skills.operator-attr-skill = "${operatorAttrSkill}";
  };

  # The operator's own skills as a whole directory (path form).
  # Setting this single-valued option to a path also proves the module never
  # contributes to it, since an attribute-set contribution would clash with the
  # path at eval.
  wholeDirSkills = homeFiles {
    programs.claude-code.enable = true;
    programs.agents.skills = [ skillAlpha ];
    programs.claude-code.skills = "${operatorSkillsDir}";
  };

  # A non-default `configDir`, so the assertions can prove placement follows it
  # rather than a hardcoded `.claude`.
  customConfigDir = homeFiles {
    programs.claude-code.enable = true;
    programs.claude-code.configDir = "/home/operator/.config/claude";
    programs.agents.skills = [ skillAlpha ];
  };

  # Pi enabled and Claude Code disabled.
  piOnly = homeFiles {
    programs.pi-coding-agent.enable = true;
    programs.agents.skills = [ skillAlpha ];
  };

  # Both supported harnesses enabled.
  bothHarnesses = homeFiles {
    programs.claude-code.enable = true;
    programs.pi-coding-agent.enable = true;
    programs.agents.skills = [ skillAlpha ];
  };

  # A non-default Pi `configDir`, so the assertions can prove placement follows it
  # rather than a hardcoded `.pi/agent`.
  customPiConfigDir = homeFiles {
    programs.pi-coding-agent.enable = true;
    programs.pi-coding-agent.configDir = "/home/operator/.config/pi/agent";
    programs.agents.skills = [ skillAlpha ];
  };

  # No compatible harness enabled, with a skill still selected.
  agentsOff = homeFiles {
    programs.claude-code.enable = false;
    programs.pi-coding-agent.enable = false;
    programs.agents.skills = [ skillAlpha ];
  };

  # An empty selection with both supported harnesses enabled.
  emptySelection = homeFiles {
    programs.claude-code.enable = true;
    programs.pi-coding-agent.enable = true;
    programs.agents.skills = [ ];
  };
in
pkgs.runCommandLocal "skills-home-manager-module-check"
  {
    # Forcing each derivation as a build input builds its home-files tree, so an
    # eval-level composition failure surfaces before any assertion runs.
    inherit
      attrSetSkills
      wholeDirSkills
      customConfigDir
      piOnly
      bothHarnesses
      customPiConfigDir
      agentsOff
      emptySelection
      ;
  }
  ''
    fail() { echo "FAIL: $1" >&2; exit 1; }

    echo "attribute-set skills: both selected skills and the operator's own land"
    test -f "$attrSetSkills/.claude/skills/sample-alpha/SKILL.md" \
      || fail "selected skill sample-alpha did not land at its own name"
    test -f "$attrSetSkills/.claude/skills/sample-beta/SKILL.md" \
      || fail "selected skill sample-beta did not land at its own name"
    test -f "$attrSetSkills/.claude/skills/operator-attr-skill/SKILL.md" \
      || fail "the operator's own attribute-set skill was clobbered"

    echo "recursive placement: a skill is a real directory of per-file symlinks"
    # A file-existence test follows symlinks, so it cannot tell a recursive tree
    # from one opaque symlink over the whole skill.
    # The entry's own type is what the assertion reads instead.
    test -d "$attrSetSkills/.claude/skills/sample-alpha" \
      && test ! -L "$attrSetSkills/.claude/skills/sample-alpha" \
      || fail "sample-alpha was placed as an opaque symlink, not a recursive tree"

    echo "whole-directory skills: the selected skill lands beside the operator's directory"
    test -f "$wholeDirSkills/.claude/skills/sample-alpha/SKILL.md" \
      || fail "selected skill did not coexist with a whole skills directory"
    test -f "$wholeDirSkills/.claude/skills/operator-dir-skill/SKILL.md" \
      || fail "the operator's whole skills directory was clobbered"

    echo "custom configDir: placement follows configDir rather than a hardcoded .claude"
    test -f "$customConfigDir/.config/claude/skills/sample-alpha/SKILL.md" \
      || fail "skill was not placed under the configured configDir"
    test ! -e "$customConfigDir/.claude/skills/sample-alpha" \
      || fail "skill was placed under a hardcoded .claude, ignoring configDir"

    echo "Pi enabled: selected skills land in Pi's global skills directory"
    test -f "$piOnly/.pi/agent/skills/sample-alpha/SKILL.md" \
      || fail "selected skill did not land under Pi's configDir"
    test ! -e "$piOnly/.claude/skills/sample-alpha" \
      || fail "a skill was placed for Claude Code when only Pi was enabled"

    echo "both harnesses enabled: selected skills land in both global skills directories"
    test -f "$bothHarnesses/.claude/skills/sample-alpha/SKILL.md" \
      || fail "selected skill did not land under Claude Code when both harnesses were enabled"
    test -f "$bothHarnesses/.pi/agent/skills/sample-alpha/SKILL.md" \
      || fail "selected skill did not land under Pi when both harnesses were enabled"

    echo "custom Pi configDir: placement follows configDir rather than a hardcoded .pi/agent"
    test -f "$customPiConfigDir/.config/pi/agent/skills/sample-alpha/SKILL.md" \
      || fail "skill was not placed under Pi's configured configDir"
    test ! -e "$customPiConfigDir/.pi/agent/skills/sample-alpha" \
      || fail "skill was placed under a hardcoded .pi/agent, ignoring configDir"

    echo "agents disabled: no skill entry is written despite a selection"
    test ! -e "$agentsOff/.claude/skills/sample-alpha" \
      || fail "a skill was placed with Claude Code disabled"
    test ! -e "$agentsOff/.pi/agent/skills/sample-alpha" \
      || fail "a skill was placed with Pi disabled"

    echo "empty selection: nothing is installed"
    test ! -e "$emptySelection/.claude/skills/sample-alpha" \
      || fail "an unselected skill was placed for Claude Code"
    test ! -e "$emptySelection/.pi/agent/skills/sample-alpha" \
      || fail "an unselected skill was placed for Pi"

    touch "$out"
  ''