package main

// The agent's session from the operator's shell (novox/hq ADR 0266): where a machine names an account of the
// agents' own, `claude` typed in the operator's interactive zsh is `claude-agent`; where agents run as the
// operator's account, nothing is added. The manifest writes the account agents run as to a file, and the zsh
// code it contributes reads it: the controller never fills a machine fact into shell code.

import (
	"encoding/json"
	"os"
	"os/exec"
	"os/user"
	"path/filepath"
	"strings"
	"testing"
)

const agentAccountFile = "/etc/claude-code/agent-account"

type manifestShell struct {
	Resources []map[string]any `json:"resources"`
	// The zsh code is an item of the collection shell:zsh:<slot> (novox/hq ADR 0349 clause 13), its text the
	// template file beside the manifest.
	Items []struct {
		Collection string `json:"collection"`
		Template   string `json:"template"`
	} `json:"items"`
}

func readManifestShell(t *testing.T) manifestShell {
	t.Helper()
	raw, err := os.ReadFile("../../module.json")
	if err != nil {
		t.Fatal(err)
	}
	var m manifestShell
	if err := json.Unmarshal(raw, &m); err != nil {
		t.Fatal(err)
	}
	return m
}

func resourceByID(t *testing.T, m manifestShell, id string) map[string]any {
	t.Helper()
	for _, r := range m.Resources {
		if r["id"] == id {
			return r
		}
	}
	t.Fatalf("the manifest has no resource %q", id)
	return nil
}

// zshCode is the one piece of zsh code the module contributes.
func zshCode(t *testing.T, m manifestShell) string {
	t.Helper()
	var code []string
	for _, it := range m.Items {
		if strings.HasPrefix(it.Collection, "shell:zsh:") {
			text, err := os.ReadFile(filepath.Join("..", "..", it.Template))
			if err != nil {
				t.Fatal(err)
			}
			code = append(code, string(text))
		}
	}
	if len(code) != 1 {
		t.Fatalf("the module contributes %d pieces of zsh code; one is expected", len(code))
	}
	return code[0]
}

// The file names the account agents run as, from the machine fact, which is the operator's where none is named.
func TestTheAccountAgentsRunAsIsWrittenForTheShell(t *testing.T) {
	r := resourceByID(t, readManifestShell(t), "agent-account-name")
	if r["type"] != "file" || r["path"] != agentAccountFile || r["mode"] != "0644" {
		t.Fatalf("the account's file is %v", r)
	}
	if text := templateText(t, r); text != "${machine:agent-account}\n" {
		t.Fatalf("the account's file holds %q", text)
	}
	if _, has := r["owner"]; has {
		t.Fatal("the account's file must be root's, as claude-agent is")
	}
}

// The alias stands once, and only inside the guard that compares the account with the shell's own.
func TestTheAliasStandsOnlyBehindTheGuard(t *testing.T) {
	code := zshCode(t, readManifestShell(t))
	if n := strings.Count(code, "alias claude="); n != 1 {
		t.Fatalf("the code names the alias %d times", n)
	}
	lines := strings.Split(code, "\n")
	guard, alias, end := -1, -1, -1
	for i, l := range lines {
		l = strings.TrimSpace(l)
		switch {
		case l == "if [[ -n $agent && $agent != $USERNAME ]]; then":
			guard = i
		case l == "alias claude=claude-agent":
			alias = i
		case l == "fi" && guard >= 0 && alias > guard && end < 0:
			end = i
		}
	}
	if guard < 0 || alias < 0 || end < 0 || !(guard < alias && alias < end) {
		t.Fatalf("the alias is not inside the guard:\n%s", code)
	}
	if strings.Contains(code, "${") {
		t.Fatal("the code holds ${…}, which the controller does not fill in shell code and zsh reads as its own")
	}
}

// Run in zsh, the code adds the alias only where the file names an account other than the shell's.
func TestTheCodeAddsTheAliasOnlyForAnotherAccount(t *testing.T) {
	zsh, err := exec.LookPath("zsh")
	if err != nil {
		t.Skip("no zsh here")
	}
	me, err := user.Current()
	if err != nil {
		t.Fatal(err)
	}
	code := zshCode(t, readManifestShell(t))
	cases := []struct {
		name    string
		content *string
		alias   bool
	}{
		{"an agent account of its own", ptr("agent-of-its-own\n"), true},
		{"agents run as the operator's account", ptr(me.Username + "\n"), false},
		{"an empty file", ptr(""), false},
		{"no file", nil, false},
	}
	for _, c := range cases {
		t.Run(c.name, func(t *testing.T) {
			file := filepath.Join(t.TempDir(), "agent-account")
			if c.content != nil {
				if err := os.WriteFile(file, []byte(*c.content), 0o644); err != nil {
					t.Fatal(err)
				}
			}
			script := strings.ReplaceAll(code, agentAccountFile, file) + "alias claude || true\n"
			out, err := exec.Command(zsh, "-f", "-c", script).CombinedOutput()
			if err != nil {
				t.Fatalf("%v: %s", err, out)
			}
			got := strings.TrimSpace(string(out))
			if c.alias && got != "claude=claude-agent" {
				t.Fatalf("no alias: %q", got)
			}
			if !c.alias && got != "" {
				t.Fatalf("an alias, or output, where none belongs: %q", got)
			}
		})
	}
}

// claude-agent runs the real claude, never itself: with the alias in force in the shell that types claude,
// claude-agent's own `exec claude` finds the program on PATH, since an alias is a word of an interactive zsh
// and neither exec, sudo nor claude-agent's sh sees it.
func TestClaudeAgentRunsTheRealClaudeUnderTheAlias(t *testing.T) {
	zsh, err := exec.LookPath("zsh")
	if err != nil {
		t.Skip("no zsh here")
	}
	me, err := user.Current()
	if err != nil {
		t.Fatal(err)
	}
	start := templateText(t, resourceByID(t, readManifestShell(t), "start"))
	if !strings.Contains(start, "exec claude \"$@\"") {
		t.Fatalf("claude-agent no longer runs claude itself:\n%s", start)
	}
	bin := t.TempDir()
	// Rendered for an account that is the caller's own, the branch that runs claude without sudo.
	// A line after the shebang says the call went through it.
	agent := strings.ReplaceAll(start, "${machine:agent-account}", me.Username)
	agent = strings.Replace(agent, "\n", "\necho through claude-agent\n", 1)
	if err := os.WriteFile(filepath.Join(bin, "claude-agent"), []byte(agent), 0o755); err != nil {
		t.Fatal(err)
	}
	if err := os.WriteFile(filepath.Join(bin, "claude"), []byte("#!/bin/sh\necho \"the real claude $*\"\n"), 0o755); err != nil {
		t.Fatal(err)
	}
	// zsh reads a -c string whole before it runs any of it, so the typed line is read after the alias, by eval.
	cmd := exec.Command(zsh, "-f", "-c", "alias claude=claude-agent\neval 'claude --resume'\n")
	cmd.Env = append(os.Environ(), "PATH="+bin+string(os.PathListSeparator)+os.Getenv("PATH"))
	out, err := cmd.CombinedOutput()
	if err != nil {
		t.Fatalf("%v: %s", err, out)
	}
	if got := strings.TrimSpace(string(out)); got != "through claude-agent\nthe real claude --resume" {
		t.Fatalf("claude under the alias ran %q", got)
	}
}

func ptr(s string) *string { return &s }