gbr-games/cmd/gbrgames/draft.go

package main

import (
	"bytes"
	"encoding/json"
	"errors"
	"flag"
	"fmt"
	"io"
	"net/http"
	"os"
	"os/exec"
	"path"
	"path/filepath"
	"regexp"
	"sort"
	"strings"
	"time"

	"github.com/santhosh-tekuri/jsonschema/v6"
)

// draft writes a first template for a new game with an AI model: it gives the model AUTHORING.md as its
// rules, the facts read from the image (inspect-image) and, when available, a first-boot report, plus two
// working templates as examples. The answer is written to games/<id>/ and checked with the same validator
// and image checks as any template; problems go back to the model to fix, a few rounds at most.

type chatMessage struct {
	Role    string `json:"role"`
	Content string `json:"content"`
}

type model interface {
	chat(messages []chatMessage, schema map[string]any) (string, error)
	name() string
}

func runDraft(args []string) error {
	fs := flag.NewFlagSet("draft", flag.ExitOnError)
	gamesDir := fs.String("games", "games", "directory holding one folder per game")
	schemaDir := fs.String("schemas", "schema", "directory holding the JSON Schemas")
	gameName := fs.String("name", "", "the game's name, e.g. \"Valheim\"")
	id := fs.String("id", "", "folder/id for the new game (default: from -name)")
	image := fs.String("image", "", "Docker image the server runs in")
	steamApp := fs.String("steam-app", "", "SteamCMD app id, if the server is installed with SteamCMD")
	notes := fs.String("notes", "", "anything else the model should know (variant, crossplay plugin...)")
	reportPath := fs.String("first-boot", "", "a first-boot report.json for this image")
	provider := fs.String("provider", "ollama", "ollama or gemini")
	modelName := fs.String("model", "", "model name (default qwen3.8:27b for ollama, gemini-3.5-flash for gemini)")
	attempts := fs.Int("attempts", 3, "fix rounds after the first draft")
	noPull := fs.Bool("no-pull", false, "use the local image instead of pulling it")
	fs.Parse(args)

	if *gameName == "" || *image == "" {
		return errors.New("draft needs -name and -image")
	}
	var report *bootReport
	if *reportPath != "" {
		var err error
		if report, err = readBootReport(*reportPath); err != nil {
			return err
		}
	}
	d, err := newDrafter(draftJob{GamesDir: *gamesDir, SchemaDir: *schemaDir, Name: *gameName, ID: *id, Image: *image,
		SteamApp: *steamApp, Notes: *notes, Report: report, Provider: *provider, Model: *modelName, NoPull: *noPull})
	if err != nil {
		return err
	}
	if problems, err := d.refine(*attempts, nil); err != nil {
		return err
	} else if len(problems) > 0 {
		return fmt.Errorf("draft still has problems after %d fix rounds; it is in %s for a person to finish", *attempts, d.dir)
	}
	fmt.Println("[draft] next: review it, then boot-test it (build / CI) before opening a PR")
	return nil
}

type draftJob struct {
	GamesDir, SchemaDir string
	Name, ID, Image     string
	SteamApp, Notes     string
	Report              *bootReport
	Provider, Model     string
	NoPull              bool
}

// drafter holds one conversation with the model about one game, so later problems (a failed boot) can
// be sent back to it with everything it was told before.
type drafter struct {
	job                    draftJob
	dir, id                string
	m                      model
	facts                  *imageFacts
	gameSchema, testSchema *jsonschema.Schema
	answerSchema           map[string]any
	messages               []chatMessage
	rounds                 int
}

func newDrafter(j draftJob) (*drafter, error) {
	id := j.ID
	if id == "" {
		id = gameID(j.Name)
	}
	d := &drafter{job: j, id: id, dir: filepath.Join(j.GamesDir, id)}
	if _, err := os.Stat(d.dir); err == nil {
		return nil, fmt.Errorf("%s already exists; drafts only create new games", d.dir)
	}
	var err error
	if d.m, err = newModel(j.Provider, j.Model); err != nil {
		return nil, err
	}
	rules, err := os.ReadFile("AUTHORING.md")
	if err != nil {
		return nil, fmt.Errorf("AUTHORING.md (the model's rules): %w", err)
	}
	if d.gameSchema, err = compileSchema(filepath.Join(j.SchemaDir, "game.schema.json")); err != nil {
		return nil, err
	}
	if d.testSchema, err = compileSchema(filepath.Join(j.SchemaDir, "test.schema.json")); err != nil {
		return nil, err
	}
	if d.answerSchema, err = draftAnswerSchema(j.SchemaDir); err != nil {
		return nil, err
	}
	if !j.NoPull {
		fmt.Printf("[draft] pulling %s\n", j.Image)
		if out, err := runCmd("docker", "pull", "-q", j.Image); err != nil {
			return nil, fmt.Errorf("docker pull: %v: %s", err, out)
		}
	}
	if d.facts, err = inspectImage(j.Image, nil); err != nil {
		return nil, err
	}
	if why := imageUnusable(j.Report); why != "" {
		return nil, errors.New(why)
	}
	d.messages = []chatMessage{
		{Role: "system", Content: draftSystemPrompt(string(rules))},
		{Role: "user", Content: draftRequest(j.Name, id, j.Image, j.SteamApp, j.Notes, d.facts, j.Report, exampleTemplates(j.GamesDir, 2))},
	}
	return d, nil
}

func gameID(name string) string {
	return strings.Trim(regexp.MustCompile(`[^a-z0-9]+`).ReplaceAllString(strings.ToLower(name), "-"), "-")
}

// refine asks for a (corrected) template until it passes validation and the image checks, at most
// attempts+1 answers. feedback, when given, is what went wrong since the last answer (e.g. its boot).
// It returns the problems still left, nil when the draft passes.
func (d *drafter) refine(attempts int, feedback []string) ([]string, error) {
	if len(feedback) > 0 {
		d.ask(feedback)
	}
	var problems []string
	for round := 0; round <= attempts; round++ {
		d.rounds++
		fmt.Printf("[draft] round %d: asking %s\n", d.rounds, d.m.name())
		start := time.Now()
		answer, err := d.m.chat(d.messages, d.answerSchema)
		if err != nil {
			return nil, err
		}
		fmt.Printf("[draft] answer in %.0fs\n", time.Since(start).Seconds())
		d.messages = append(d.messages, chatMessage{Role: "assistant", Content: answer})

		if problems = d.check(answer); len(problems) == 0 {
			fmt.Printf("[draft] %s passes validation and the image checks\n", d.dir)
			return nil, nil
		}
		fmt.Printf("[draft] %d problem(s):\n", len(problems))
		for _, p := range problems {
			fmt.Println("        - " + p)
		}
		if round < attempts {
			d.ask(problems)
		}
	}
	return problems, nil
}

func (d *drafter) ask(problems []string) {
	d.messages = append(d.messages, chatMessage{Role: "user", Content: "Your template has these problems. Fix all of them and " +
		"answer with the complete corrected JSON object (both \"game\" and \"test\"):\n- " + strings.Join(problems, "\n- ")})
}

func (d *drafter) check(answer string) []string {
	problems := writeDraft(d.dir, d.id, answer, d.job.Report)
	if len(problems) == 0 {
		problems = validateGame(d.dir, d.id, d.gameSchema, d.testSchema)
	}
	if len(problems) == 0 {
		if g, err := loadMap(filepath.Join(d.dir, "game.yaml")); err == nil {
			imageProblems, _ := checkTemplate(g, d.facts)
			problems = append(problems, imageProblems...)
			t, _ := loadMap(filepath.Join(d.dir, "test.yaml"))
			problems = append(problems, draftCompleteness(g, t)...)
			problems = append(problems, unreadSettings(g, d.facts)...)
			problems = append(problems, savesOutsideVolumes(g, d.job.Report)...)
		}
	}
	return problems
}

func readBootReport(p string) (*bootReport, error) {
	raw, err := os.ReadFile(p)
	if err != nil {
		return nil, err
	}
	r := &bootReport{}
	if err := json.Unmarshal(raw, r); err != nil {
		return nil, fmt.Errorf("%s: %w", p, err)
	}
	return r, nil
}

func draftSystemPrompt(rules string) string {
	return "You write game server templates for GBR Hosting. Follow these house rules exactly; they describe " +
		"how servers really run, and breaking them has broken real servers:\n\n" + rules + "\n\n" +
		"Answer with one JSON object and nothing else: {\"game\": <the game.yaml content as JSON>, " +
		"\"test\": <the test.yaml content as JSON>}.\n\n" +
		"The template must be COMPLETE enough for a player to run and configure the server:\n" +
		"- defaultPorts: every port players or the server browser connect to (from the image's exposed ports " +
		"and the game's documentation), each with its protocol. Never RCON/REST/admin or web/status ports.\n" +
		"- defaultConfig and configSchema: every setting the image reads (the facts' envRead and env lists, the " +
		"first-boot settings) that an owner would want to change: server name, world, password, player limit, " +
		"difficulty and gameplay options. Each with title, description, type, default and category.\n" +
		"- requiredMemoryMb: what the game really needs, with headroom.\n" +
		"- readyPattern when a first-boot report shows the ready line; otherwise set test.settleSec.\n" +
		"Base every value on the facts given (image facts, first-boot report) and on what you know for certain " +
		"about this game and image. Do not invent settings an image does not read; say what you are unsure of " +
		"in the setting's description instead of leaving the template empty."
}

// draftCompleteness is the bar a draft must clear on top of validation: an almost empty template is
// valid but useless, and a cautious model will happily produce one.
func draftCompleteness(game, test map[string]any) []string {
	var problems []string
	if ports, _ := game["defaultPorts"].([]any); len(ports) == 0 {
		problems = append(problems, "defaultPorts is empty: list the ports players connect to")
	}
	props := schemaProperties(game)
	defaults, _ := game["defaultConfig"].(map[string]any)
	if len(defaults) < 3 {
		problems = append(problems, fmt.Sprintf("defaultConfig has only %d settings: add every setting the image reads that an owner would change (name, world, password, players, gameplay)", len(defaults)))
	}
	var undescribed []string
	for _, key := range sortedKeys(defaults) {
		if _, ok := props[key]; !ok {
			undescribed = append(undescribed, key)
		}
	}
	if len(undescribed) > 0 {
		problems = append(problems, "these defaultConfig settings have no configSchema.properties entry (each needs title, description, "+
			"type, default and category, under configSchema: {type: object, properties: {...}}): "+strings.Join(undescribed, ", "))
	}
	for _, key := range sortedKeys(props) {
		p, _ := props[key].(map[string]any)
		for _, field := range []string{"title", "description", "type", "category"} {
			if v, ok := p[field]; !ok || v == "" {
				problems = append(problems, fmt.Sprintf("setting %s has no %s", key, field))
			}
		}
	}
	if n, ok := game["requiredMemoryMb"].(json.Number); !ok {
		problems = append(problems, "requiredMemoryMb is missing")
	} else if v, _ := n.Int64(); v < 1024 {
		problems = append(problems, "requiredMemoryMb is below 1024")
	}
	if _, ok := game["readyPattern"]; !ok {
		if _, ok := test["settleSec"]; !ok {
			problems = append(problems, "no readyPattern and no test.settleSec: boot tests need one of them")
		}
	}
	return problems
}

// unreadSettings finds settings that reach the container under a variable name the image never reads,
// e.g. ServerPassword -> SERVER_PASSWORD when the image reads SERVER_PASS. Only for images configured
// through environment variables (no config file) whose startup scripts the inspector could read.
func unreadSettings(game map[string]any, facts *imageFacts) []string {
	if path, _ := game["configFilePath"].(string); path != "" || len(facts.EnvRead) == 0 {
		return nil
	}
	read := map[string]bool{}
	for _, v := range facts.EnvRead {
		read[v] = true
	}
	for v := range facts.Env {
		read[v] = true
	}
	startup, _ := game["defaultStartupCommand"].(string)
	defaults, _ := game["defaultConfig"].(map[string]any)
	var problems []string
	for _, key := range sortedKeys(defaults) {
		env := envName(key)
		if read[env] || strings.Contains(startup, env) {
			continue
		}
		msg := fmt.Sprintf("setting %s reaches the container as %s, which the image never reads", key, env)
		if near := closestVar(env, facts.EnvRead); near != "" {
			msg += fmt.Sprintf(" (did you mean %s? name the key so it becomes that)", near)
		}
		problems = append(problems, msg)
	}
	return problems
}

// closestVar picks the variable that shares the longest common prefix with name (SERVER_PASSWORD ->
// SERVER_PASS), if it's a real resemblance.
func closestVar(name string, vars []string) string {
	best, bestLen := "", 0
	for _, v := range vars {
		n := 0
		for n < len(v) && n < len(name) && v[n] == name[n] {
			n++
		}
		if n > bestLen {
			best, bestLen = v, n
		}
	}
	if bestLen < 5 {
		return ""
	}
	return best
}

// Files the Steam client, Proton and the OS write for themselves: not the game's data
var outsideNoise = []string{"/Steam/logs/", "/.steam/", "/steamcmd/", "/.cache/", "/tmp/", "/.local/share/umu"}

// savesOutsideVolumes turns first boot's "written outside the volumes" into a hard check: anything the
// game itself wrote there (Valheim's worlds and admin lists in ~/.config/unity3d/...) is lost every time the
// node recreates the container. A template passes once its startup command or settings point the game at
// /server or /data; a boot test then shows whether that really worked.
func savesOutsideVolumes(game map[string]any, report *bootReport) []string {
	dirs := outsideDirs(report)
	if len(dirs) == 0 {
		return nil
	}
	startup, _ := game["defaultStartupCommand"].(string)
	redirected := strings.Contains(startup, "/server") || strings.Contains(startup, "/data")
	defaults, _ := game["defaultConfig"].(map[string]any)
	for _, v := range defaults {
		if s, ok := v.(string); ok && (strings.HasPrefix(s, "/server") || strings.HasPrefix(s, "/data")) {
			redirected = true
		}
	}
	if redirected {
		return nil
	}
	return []string{fmt.Sprintf("first boot: the server wrote its own files outside the server volume, in %s. Those are lost "+
		"whenever the node recreates the container (every start). Make the game keep them under /server, e.g. with "+
		"its save-directory launch option or by pointing that folder at /server, and include it in backupPaths",
		strings.Join(dirs, ", "))}
}

// outsideDirs lists the folders outside the volumes where the game itself wrote files during a boot.
func outsideDirs(report *bootReport) []string {
	if report == nil {
		return nil
	}
	dirs := map[string]bool{}
	for _, c := range report.ContainerChanges {
		_, p, _ := strings.Cut(c, " ")
		noise := false
		for _, n := range outsideNoise {
			if strings.Contains(p, n) {
				noise = true
			}
		}
		if !noise && p != "" {
			dirs[path.Dir(p)] = true
		}
	}
	return sortedKeysBool(dirs)
}

// imageUnusable recognises a first boot where the image died within seconds because it needs root (or
// another privilege nodes never grant): drafting a template for it can't produce a working server.
func imageUnusable(r *bootReport) string {
	if r == nil || r.ExitCode == nil || *r.ExitCode == 0 || r.RanSeconds > 60 {
		return ""
	}
	var denied []string
	for _, l := range r.ErrorLines {
		if strings.Contains(strings.ToLower(l.Text), "permission denied") {
			denied = append(denied, l.Text)
		}
	}
	if len(denied) == 0 {
		return ""
	}
	return fmt.Sprintf("first boot: the image exited (code %d) after %.0fs as %s with permission errors, e.g. %q. It needs root, "+
		"which nodes never allow; use another image for this game, or cm2network/steamcmd with -steam-app",
		*r.ExitCode, r.RanSeconds, r.User, denied[0])
}

func draftRequest(gameName, id, image, steamApp, notes string, facts *imageFacts, report *bootReport, examples string) string {
	var b strings.Builder
	fmt.Fprintf(&b, "Write the template for **%s**.\n- id: %s\n- defaultDockerImage: %s\n", gameName, id, image)
	if steamApp != "" {
		fmt.Fprintf(&b, "- installMethod STEAMCMD with appId %s\n", steamApp)
	}
	if notes != "" {
		fmt.Fprintf(&b, "- notes: %s\n", notes)
	}

	f := *facts
	f.Scripts = map[string]string{}
	for p, s := range facts.Scripts {
		if len(s) > 8000 {
			s = s[:8000] + "\n...(truncated)"
		}
		f.Scripts[p] = s
	}
	fj, _ := json.MarshalIndent(f, "", " ")
	fmt.Fprintf(&b, "\n## Facts read from the image (inspect-image)\n```json\n%s\n```\n", fj)

	if report != nil {
		fmt.Fprintf(&b, "\n## First boot with no settings\nOutcome: %s\n", report.Outcome)
		if report.SuggestedReady != "" {
			fmt.Fprintf(&b, "Suggested readyPattern: `%s` (readyExample: `%s`)\n", report.SuggestedReady, report.SuggestedExample)
		}
		for _, l := range report.ReadyCandidates {
			fmt.Fprintf(&b, "ready-looking line: %s\n", l.Text)
		}
		for _, l := range report.ErrorLines {
			fmt.Fprintf(&b, "error-looking line: %s\n", l.Text)
		}
		fmt.Fprintf(&b, "Config files the server wrote: %s\n", strings.Join(report.ConfigFiles, ", "))
		settings := report.Settings
		if len(settings) > 300 {
			settings = settings[:300]
		}
		b.WriteString("Settings it wrote, with defaults (file | section | key = value):\n")
		for _, s := range settings {
			fmt.Fprintf(&b, "%s | %s | %s = %s\n", s.File, s.Section, s.Key, s.Value)
		}
	} else {
		b.WriteString("\n(No first-boot report: keep readyPattern out unless the facts show the ready line.)\n")
	}
	b.WriteString("\n## Working templates from this repo, for format and style (not content)\n")
	b.WriteString(examples)
	return b.String()
}

// exampleTemplates picks the shortest templates in the repo as examples: real, validated, and small
// enough to leave the model room for the facts.
func exampleTemplates(gamesDir string, n int) string {
	entries, _ := os.ReadDir(gamesDir)
	type ex struct {
		id   string
		body string
	}
	var all []ex
	for _, e := range entries {
		raw, err := os.ReadFile(filepath.Join(gamesDir, e.Name(), "game.yaml"))
		if err == nil {
			all = append(all, ex{e.Name(), string(raw)})
		}
	}
	sort.Slice(all, func(i, j int) bool { return len(all[i].body) < len(all[j].body) })
	var b strings.Builder
	for i := 0; i < n && i < len(all); i++ {
		fmt.Fprintf(&b, "\n### games/%s/game.yaml\n```yaml\n%s```\n", all[i].id, all[i].body)
	}
	return b.String()
}

// writeDraft turns the model's JSON answer into games/<id>/game.yaml and test.yaml, using the importer's
// writer so drafts look like every other template.
func writeDraft(dir, id, answer string, report *bootReport) []string {
	answer = trimToJSON(answer)
	var parsed struct {
		Game map[string]any `json:"game"`
		Test map[string]any `json:"test"`
	}
	if err := json.Unmarshal([]byte(answer), &parsed); err != nil {
		return []string{"the answer is not valid JSON: " + err.Error()}
	}
	if parsed.Game == nil {
		return []string{`the answer has no "game" object`}
	}
	parsed.Game["id"] = id
	if parsed.Test == nil {
		parsed.Test = map[string]any{}
	}
	// The ready line is a fact from the first boot, already checked against the real log line; a model
	// that leaves it out (or answers null) gets the measured one rather than another guessing round
	if p, _ := parsed.Game["readyPattern"].(string); p == "" && report != nil && report.SuggestedReady != "" {
		parsed.Game["readyPattern"] = report.SuggestedReady
		parsed.Test["readyExample"] = report.SuggestedExample
	}
	if err := os.MkdirAll(dir, 0o755); err != nil {
		return []string{err.Error()}
	}
	var problems []string
	known := map[string]bool{}
	for _, f := range gameFields {
		known[f] = true
	}
	for k := range parsed.Game {
		if !known[k] {
			problems = append(problems, fmt.Sprintf("%q is not a template field; remove it or use one from the schema", k))
		}
	}
	if err := writeGame(filepath.Join(dir, "game.yaml"), parsed.Game); err != nil {
		return []string{"could not write game.yaml: " + err.Error()}
	}
	node, err := toNode(normalize(parsed.Test))
	if err != nil {
		return []string{err.Error()}
	}
	if err := writeYAML(filepath.Join(dir, "test.yaml"), testHeader, node); err != nil {
		return []string{"could not write test.yaml: " + err.Error()}
	}
	return problems
}

// draftAnswerSchema is the shape Ollama is asked to produce: {"game": ..., "test": ...}, using the repo's
// schemas minus the parts structured-output engines don't support.
func draftAnswerSchema(schemaDir string) (map[string]any, error) {
	load := func(name string) (map[string]any, error) {
		raw, err := os.ReadFile(filepath.Join(schemaDir, name))
		if err != nil {
			return nil, err
		}
		var s map[string]any
		if err := json.Unmarshal(raw, &s); err != nil {
			return nil, err
		}
		for _, k := range []string{"$schema", "$id", "allOf", "title", "description"} {
			delete(s, k)
		}
		return s, nil
	}
	game, err := load("game.schema.json")
	if err != nil {
		return nil, err
	}
	test, err := load("test.schema.json")
	if err != nil {
		return nil, err
	}
	tightenForDraft(game)
	return map[string]any{
		"type":                 "object",
		"required":             []string{"game", "test"},
		"properties":           map[string]any{"game": game, "test": test},
		"additionalProperties": false,
	}, nil
}

// tightenForDraft makes the fields a working template needs required and non-null in the format Ollama
// enforces. The repo schema leaves them optional (hand-written templates may omit some), and a constrained
// model takes that literally: it answered null for installConfig, defaultConfig and configSchema, the
// writer dropped them, and no amount of "add installConfig" could change that.
func tightenForDraft(game map[string]any) {
	props, _ := game["properties"].(map[string]any)
	nonNull := func(name, typ string) {
		if p, ok := props[name].(map[string]any); ok {
			p["type"] = typ
		}
	}
	nonNull("defaultStartupCommand", "string")
	nonNull("requiredMemoryMb", "integer")
	nonNull("defaultPorts", "array")
	if p, ok := props["defaultPorts"].(map[string]any); ok {
		p["minItems"] = 1
	}
	props["installConfig"] = map[string]any{
		"type": "object",
		"properties": map[string]any{
			"appId":  map[string]any{"type": "string", "description": "Steam app id, for installMethod STEAMCMD"},
			"script": map[string]any{"type": "string", "description": "install script, for installMethod BASH_SCRIPT"},
		},
	}
	props["defaultConfig"] = map[string]any{"type": "object", "minProperties": 3}
	props["configSchema"] = map[string]any{
		"type":     "object",
		"required": []string{"type", "properties"},
		"properties": map[string]any{
			"type": map[string]any{"enum": []string{"object"}},
			"properties": map[string]any{
				"type":          "object",
				"minProperties": 3,
				"additionalProperties": map[string]any{
					"type":     "object",
					"required": []string{"title", "description", "type", "default", "category"},
					"properties": map[string]any{
						"title":       map[string]any{"type": "string"},
						"description": map[string]any{"type": "string"},
						"type":        map[string]any{"enum": []string{"string", "integer", "number", "boolean"}},
						"category":    map[string]any{"enum": []string{"Security & Access", "Gameplay & Rules", "World & Environment", "System & General"}},
					},
				},
			},
		},
	}
	game["required"] = []string{"id", "name", "defaultDockerImage", "defaultStartupCommand", "requiredMemoryMb",
		"defaultPorts", "installMethod", "installConfig", "defaultConfig", "configSchema"}
}

func newModel(provider, name string) (model, error) {
	switch provider {
	case "ollama":
		if name == "" {
			name = "qwen3.8:27b"
		}
		url := os.Getenv("OLLAMA_URL")
		if url == "" {
			url = "http://localhost:11434"
		}
		return &ollamaModel{url: strings.TrimRight(url, "/"), model: name}, nil
	case "gemini":
		if name == "" {
			name = "gemini-3.5-flash"
		}
		key := os.Getenv("GEMINI_API_KEY")
		if key == "" {
			return nil, errors.New("set GEMINI_API_KEY to use -provider gemini")
		}
		return &geminiModel{key: key, model: name}, nil
	}
	return nil, fmt.Errorf("unknown provider %q (ollama or gemini)", provider)
}

type ollamaModel struct{ url, model string }

func (o *ollamaModel) name() string { return "ollama " + o.model + " at " + o.url }

func (o *ollamaModel) chat(messages []chatMessage, schema map[string]any) (string, error) {
	body := map[string]any{
		"model": o.model, "messages": messages, "stream": false, "format": schema,
		// Ollama silently truncates input beyond its default context
		"options": map[string]any{"num_ctx": 32768, "temperature": 0.2},
	}
	var resp struct {
		Message struct {
			Content string `json:"content"`
		} `json:"message"`
		Error string `json:"error"`
	}
	if err := postJSON(o.url+"/api/chat", body, &resp, 30*time.Minute); err != nil {
		return "", err
	}
	if resp.Error != "" {
		return "", errors.New("ollama: " + resp.Error)
	}
	return resp.Message.Content, nil
}

type geminiModel struct{ key, model string }

func (g *geminiModel) name() string { return "gemini " + g.model }

func (g *geminiModel) chat(messages []chatMessage, _ map[string]any) (string, error) {
	var system string
	var contents []map[string]any
	for _, m := range messages {
		if m.Role == "system" {
			system = m.Content
			continue
		}
		role := "user"
		if m.Role == "assistant" {
			role = "model"
		}
		contents = append(contents, map[string]any{"role": role, "parts": []map[string]string{{"text": m.Content}}})
	}
	body := map[string]any{
		"systemInstruction": map[string]any{"parts": []map[string]string{{"text": system}}},
		"contents":          contents,
		"generationConfig":  map[string]any{"responseMimeType": "application/json", "temperature": 0.2},
	}
	var resp struct {
		Candidates []struct {
			Content struct {
				Parts []struct {
					Text string `json:"text"`
				} `json:"parts"`
			} `json:"content"`
		} `json:"candidates"`
		Error *struct {
			Message string `json:"message"`
		} `json:"error"`
	}
	url := "https://generativelanguage.googleapis.com/v1beta/models/" + g.model + ":generateContent?key=" + g.key
	if err := postJSON(url, body, &resp, 10*time.Minute); err != nil {
		return "", err
	}
	if resp.Error != nil {
		return "", errors.New("gemini: " + resp.Error.Message)
	}
	if len(resp.Candidates) == 0 || len(resp.Candidates[0].Content.Parts) == 0 {
		return "", errors.New("gemini returned no answer")
	}
	return resp.Candidates[0].Content.Parts[0].Text, nil
}

func postJSON(url string, body, out any, timeout time.Duration) error {
	payload, err := json.Marshal(body)
	if err != nil {
		return err
	}
	client := &http.Client{Timeout: timeout}
	resp, err := client.Post(url, "application/json", bytes.NewReader(payload))
	if err != nil {
		return err
	}
	defer resp.Body.Close()
	raw, err := io.ReadAll(resp.Body)
	if err != nil {
		return err
	}
	if err := json.Unmarshal(raw, out); err != nil {
		return fmt.Errorf("HTTP %d, unreadable answer: %.300s", resp.StatusCode, raw)
	}
	return nil
}

func runCmd(name string, args ...string) (string, error) {
	out, err := exec.Command(name, args...).CombinedOutput()
	return strings.TrimSpace(string(out)), err
}