{

  inputs.nixpkgs.url = "github:nixos/nixpkgs?ref=nixos-unstable";

  outputs =
    { self, nixpkgs }:
    let
      forAllSystems =
        f: nixpkgs.lib.genAttrs nixpkgs.lib.systems.flakeExposed (sys: f nixpkgs.legacyPackages.${sys});
    in
    {
      devShells = forAllSystems (pkgs: {
        default = pkgs.mkShell {
          packages = with pkgs; [
            rustc
            cargo
            rustfmt
            rust-analyzer
            clippy
          ];
        };
      });

      packages = forAllSystems (pkgs: {
        default = pkgs.rustPlatform.buildRustPackage {
          pname = "inshellah";
          version = "0.1.1";
          src = pkgs.lib.cleanSource ./.;
          cargoLock.lockFile = ./Cargo.lock;
          meta = {
            description = "nushell completion indexer";
            mainProgram = "inshellah";
          };
        };
      });

      nixosModules.default =
        {
          pkgs,
          lib,
          config,
          ...
        }:
        {
          imports = [ ./nix/module.nix ];
          programs.inshellah.package = self.packages.${pkgs.stdenv.hostPlatform.system}.default;
          programs.inshellah.snippet = ''
            let inshellah_complete = { |spans|
                let completions = (^inshellah complete ...$spans) | from json
                let span_len = ($spans | length)
                let last_span = if $span_len > 0 { $spans | last } else { "" }
                let prev_span = if $span_len >= 2 { $spans | get ($span_len - 2) } else { "" }
                let sub = if $span_len >= 2 { $spans | get 1 } else { "" }
                # dynamic completions — fire only when the static index has nothing.
                let additional = if ($completions == null and $span_len > 0) {
                  match $spans.0 {
                    "nix" => {
                        $env.NIX_GET_COMPLETIONS = $span_len - 1
                        let nix_output = $spans | run-external $in | split row -r '\n' | str trim | skip 1
                        let entries = if (($nix_output | length) < 6 and
                          $last_span =~ "[a-zA-Z][a-zA-Z0-9_-]*#[a-zA-Z][a-zA-Z0-9_-]*") {
                            hide-env NIX_GET_COMPLETIONS
                            $env.NIX_ALLOW_UNFREE = 1
                            $env.NIX_ALLOW_BROKEN = 1
                            $nix_output | par-each { |e|
                                  try {
                                    { value: $e, description: (^nix eval --impure $e --apply "f: f.meta.description" err> /dev/null) }
                                  } catch {
                                    { value: $e, description: "" }
                                  }
                                }
                         } else {
                           $nix_output | each { |e| { value: $e, description: "" } }
                         }
                        $entries
                    }
                    "systemctl" => {
                      if $span_len < 3 { null } else {
                        let scope = if ("--user" in $spans) { [--user] } else { [] }
                        ^systemctl ...$scope list-units --all --no-pager --plain --full --no-legend $"($last_span)*"
                          | lines
                          | each { |l|
                            let parsed = $l | parse -r '(?P<unit>\S+)\s+\S+\s+\S+\s+\S+\s+(?P<desc>.*)'
                            if ($parsed | length) > 0 {
                              {value: $parsed.0.unit, description: ($parsed.0.desc | str trim)}
                            }
                          } | compact
                      }
                    }
                    "journalctl" => {
                      # unit-name completion after --unit / -u
                      if ($prev_span == "--unit" or $prev_span == "-u") {
                        let scope = if ("--user-unit" in $spans or "--user" in $spans) { [--user] } else { [] }
                        ^systemctl ...$scope list-units --all --no-pager --plain --full --no-legend $"($last_span)*"
                          | lines
                          | each { |l|
                            let parsed = $l | parse -r '(?P<unit>\S+)\s+\S+\s+\S+\s+\S+\s+(?P<desc>.*)'
                            if ($parsed | length) > 0 {
                              {value: $parsed.0.unit, description: ($parsed.0.desc | str trim)}
                            }
                          } | compact
                      } else { null }
                    }
                    "coredumpctl" => {
                      # unit names (after dump/info/debug/list verbs) and pids
                      let unit_verbs = ["dump" "info" "debug" "list"]
                      if (($sub in $unit_verbs) and $span_len >= 3) {
                        let units = (try {
                          ^systemctl list-units --all --no-pager --plain --full --no-legend $"($last_span)*"
                            | lines
                            | each { |l|
                              let p = $l | parse -r '(?P<unit>\S+)\s+\S+\s+\S+\s+\S+\s+(?P<desc>.*)'
                              if ($p | length) > 0 { { value: $p.0.unit, description: ($p.0.desc | str trim) } }
                            } | compact
                        } catch { [] })
                        let pids = (try {
                          ^coredumpctl list --no-pager --no-legend
                            | lines
                            | each { |l|
                              let p = $l | split row -r '\s+'
                              if ($p | length) >= 5 { { value: $p.4, description: $"PID ($p.4) ($p | get 9? | default "")" } }
                            } | compact
                        } catch { [] })
                        $units | append $pids
                      } else { null }
                    }
                    "loginctl" => {
                      # user / session names for loginctl <verb> ...
                      let user_verbs = ["user-status" "show-user" "enable-linger" "disable-linger" "kill-user" "terminate-user"]
                      let session_verbs = ["session-status" "show-session" "activate" "lock-session" "unlock-session" "terminate-session" "kill-session"]
                      if (($sub in $user_verbs) and $span_len >= 3) {
                        try {
                          ^loginctl list-users --no-pager --no-legend
                            | lines | each { |l|
                              let p = $l | str trim | split row -r '\s+'
                              if ($p | length) >= 2 { { value: $p.1, description: $"UID ($p.0)" } }
                            } | compact
                        } catch { null }
                      } else if (($sub in $session_verbs) and $span_len >= 3) {
                        try {
                          ^loginctl list-sessions --no-pager --no-legend
                            | lines | each { |l|
                              let p = $l | str trim | split row -r '\s+'
                              if ($p | length) >= 3 { { value: $p.0, description: $"user ($p.2)" } }
                            } | compact
                        } catch { null }
                      } else { null }
                    }
                    "machinectl" => {
                      let machine_verbs = ["status" "show" "start" "login" "shell" "enable" "disable" "poweroff" "reboot" "terminate" "kill" "bind" "copy-to" "copy-from"]
                      if (($sub in $machine_verbs) and $span_len >= 3) {
                        try {
                          ^machinectl list --no-pager --no-legend
                            | lines | each { |l|
                              let p = $l | str trim | split row -r '\s+'
                              if ($p | length) >= 1 { { value: $p.0, description: ($p | get 1? | default "") } }
                            } | compact
                        } catch { null }
                      } else { null }
                    }
                    "networkctl" => {
                      let link_verbs = ["status" "show" "up" "down" "renew" "forcerenew" "reconfigure" "delete"]
                      if (($sub in $link_verbs) and $span_len >= 3) {
                        try {
                          ^networkctl list --no-pager --no-legend
                            | lines | each { |l|
                              let p = $l | str trim | split row -r '\s+'
                              if ($p | length) >= 4 { { value: $p.1, description: $"($p.2) ($p.3)" } }
                            } | compact
                        } catch { null }
                      } else { null }
                    }
                    "hostnamectl" | "timedatectl" | "localectl" => {
                      # mostly fixed verb sets — let the static index handle these.
                      # left here as an explicit no-op for documentation.
                      null
                    }
                    "ssh" | "scp" | "sftp" => {
                      # hostnames from ~/.ssh/config + ~/.ssh/known_hosts
                      let cfg_hosts = (try {
                        open ~/.ssh/config | lines | each { |l|
                          let m = $l | parse -r '(?i)^\s*Host\s+(?P<h>.+)$'
                          if ($m | length) > 0 { $m.0.h | split row -r '\s+' } else { [] }
                        } | flatten | where { |h| not ($h | str contains '*') and not ($h | is-empty) }
                      } catch { [] })
                      let known = (try {
                        open ~/.ssh/known_hosts | lines | each { |l|
                          ($l | split row -r '\s+' | get 0? | default "") | split row ','
                        } | flatten | where { |h| (not ($h | is-empty)) and (not ($h | str starts-with '|')) and (not ($h | str starts-with '[')) }
                      } catch { [] })
                      $cfg_hosts | append $known | uniq | each { |h| { value: $h, description: "" } }
                    }
                    "docker" | "podman" => {
                      let need_container = ["exec" "logs" "inspect" "start" "stop" "restart" "rm" "kill" "attach" "cp" "top" "wait" "pause" "unpause" "port" "commit" "diff" "export"]
                      let need_image = ["run" "rmi" "tag" "push" "pull" "history" "save" "create"]
                      if ($sub in $need_container) {
                        try {
                          ^($spans.0) ps -a --format '{{.Names}}\t{{.Image}}'
                            | lines | each { |l|
                              let p = $l | split row "\t"
                              if ($p | length) >= 2 { { value: $p.0, description: $p.1 } }
                            } | compact
                        } catch { null }
                      } else if ($sub in $need_image) {
                        try {
                          ^($spans.0) images --format '{{.Repository}}:{{.Tag}}\t{{.Size}}'
                            | lines | each { |l|
                              let p = $l | split row "\t"
                              if (($p | length) >= 2) and (not ($p.0 | str ends-with ':<none>')) {
                                { value: $p.0, description: $p.1 }
                              }
                            } | compact
                        } catch { null }
                      } else { null }
                    }
                    "kubectl" => {
                      let need_resource = ["get" "describe" "delete" "edit" "logs" "exec" "port-forward" "rollout" "scale" "annotate" "label"]
                      if (($sub in $need_resource) and $span_len >= 4) {
                        let kind = $spans | get 2
                        try {
                          ^kubectl get $kind --no-headers -o "custom-columns=NAME:.metadata.name"
                            | lines | str trim
                            | where { |n| not ($n | is-empty) }
                            | each { |n| { value: $n, description: $kind } }
                        } catch { null }
                      } else { null }
                    }
                    "git" => {
                      let need_ref = ["checkout" "switch" "merge" "rebase" "branch" "log" "diff" "show" "reset" "cherry-pick" "revert" "tag" "push" "pull" "blame" "bisect"]
                      if (($sub == "worktree") and $span_len >= 3) {
                        try {
                          ^git worktree list --porcelain
                            | lines
                            | each { |l|
                              let m = $l | parse -r '^worktree\s+(?P<p>.+)$'
                              if ($m | length) > 0 { { value: $m.0.p, description: "" } }
                            } | compact
                        } catch { null }
                      } else if (($sub in $need_ref) and $span_len >= 3) {
                        try {
                          ^git for-each-ref --format='%(refname:short)%09%(objecttype)%09%(contents:subject)' refs/heads refs/remotes refs/tags
                            | lines
                            | each { |l|
                              let p = $l | split row "\t"
                              if ($p | length) >= 3 { { value: $p.0, description: $p.2 } }
                            } | compact
                        } catch { null }
                      } else { null }
                    }
                    "npm" | "pnpm" | "yarn" => {
                      # script names from the nearest package.json
                      let wants = (($spans.0 == "yarn") and $span_len >= 2) or ($sub == "run") or ($sub == "run-script")
                      if $wants {
                        try {
                          open package.json | get scripts? | default {} | transpose name cmd
                            | each { |row| { value: $row.name, description: $row.cmd } }
                        } catch { null }
                      } else { null }
                    }
                    "make" => {
                      # Makefile targets — line-leading identifier followed by ':'
                      try {
                        open Makefile | lines
                          | each { |l|
                            let m = $l | parse -r '^(?P<t>[A-Za-z0-9_./-]+)\s*:'
                            if (($m | length) > 0) and (not ($m.0.t | str starts-with '.')) {
                              { value: $m.0.t, description: "" }
                            }
                          } | compact | uniq-by value
                      } catch { null }
                    }
                    "just" => {
                      # just recipes via `just --list` (handles justfile / Justfile / .justfile)
                      try {
                        ^just --list --unsorted
                          | lines | skip 1
                          | each { |l|
                            let m = $l | parse -r '^\s+(?P<t>[A-Za-z0-9_-]+)(?:\s+\S.*)?(?:\s*#\s*(?P<d>.*))?$'
                            if ($m | length) > 0 {
                              { value: $m.0.t, description: ($m.0.d? | default "") }
                            }
                          } | compact
                      } catch { null }
                    }
                    "cargo" => {
                      let need_target = ["run" "test" "build" "bench" "check" "doc" "install"]
                      let target_flags = ["--bin" "-p" "--package" "--example" "--test" "--bench"]
                      if (($sub in $need_target) and ($prev_span in $target_flags)) {
                        try {
                          ^cargo metadata --no-deps --format-version 1
                            | from json | get packages | each { |pkg|
                              $pkg.targets | each { |t| { value: $t.name, description: ($t.kind | str join ",") } }
                            } | flatten | uniq-by value
                        } catch { null }
                      } else { null }
                    }
                    "kill" | "pkill" => {
                      try {
                        ^ps -eo pid,comm --no-headers
                          | lines
                          | each { |l|
                            let parts = $l | str trim | split row -r '\s+'
                            if ($parts | length) >= 2 {
                              let pid = $parts | get 0
                              let comm = $parts | skip 1 | str join " "
                              if ($spans.0 == "kill") { { value: $pid, description: $comm } }
                              else { { value: $comm, description: $pid } }
                            }
                          } | compact
                      } catch { null }
                    }
                    _ => { null }
                  }
                } else { null }
                let result = ($completions | default []) | append ($additional | default []) | compact
                if ($result | is-empty) { null } else { $result }
            }
            $env.config.completions.external = {enable: true, max_results: 200, completer: $inshellah_complete}
          '';
        };
    };
}