package main

import (
	"bytes"
	"encoding/json"
	"errors"
	"flag"
	"fmt"
	"os"
	"path/filepath"
	"sort"
	"strings"
)

// build turns one researched variant into a template that has really booted: first boot of the image
// untouched (facts), a draft by the model, then the draft deployed with the node-agent's own code, exactly
// as CI's boot test does. What goes wrong in that boot (a crash, an error line, saves outside the volume)
// goes back to the model, a few rounds at most. The result is a games/<id>/ folder ready for a pull request.

type buildResult struct {
	GameID   string   `json:"gameId"`
	Dir      string   `json:"dir"`
	Image    string   `json:"image"`
	Passed   bool     `json:"passed"`
	Rounds   int      `json:"rounds"`
	Verified []string `json:"verified"`
	Problems []string `json:"problems"`
	Summary  string   `json:"summary"`
	// What the builder diagnosed after each failed boot, the fix it made, and how that went
	Diagnoses []attempt `json:"diagnoses,omitempty"`
}

const defaultAgentImage = "www.gitea.gbreed.com/gbreed-public/gbr-node-agent:latest"

func runBuild(args []string) error {
	fs := flag.NewFlagSet("build", 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")
	id := fs.String("id", "", "folder/id for the new game (default: from -name)")
	variantArg := fs.String("variant", "", "the chosen variant: a research result variant as JSON, or @file")
	notes := fs.String("notes", "", "what the admin asked for")
	provider := fs.String("provider", "ollama", "ollama or gemini")
	modelName := fs.String("model", "", "model name (default as for draft)")
	attempts := fs.Int("attempts", 3, "fix rounds for validation problems, each time")
	bootRounds := fs.Int("boot-rounds", 5, "boots of the draft at most (it stops earlier when a ruled-out cause comes back)")
	out := fs.String("out", "", "write the result JSON here")
	fs.Parse(args)
	if *gameName == "" || *variantArg == "" {
		return errors.New("build needs -name and -variant")
	}
	raw := []byte(*variantArg)
	if strings.HasPrefix(*variantArg, "@") {
		var err error
		if raw, err = os.ReadFile((*variantArg)[1:]); err != nil {
			return err
		}
	}
	var v variant
	if err := json.Unmarshal(raw, &v); err != nil {
		return fmt.Errorf("-variant: %w", err)
	}
	if *id == "" {
		*id = gameID(*gameName)
	}
	agentImage := os.Getenv("AGENT_IMAGE")
	if agentImage == "" {
		agentImage = defaultAgentImage
	}

	res, err := build(buildOptions{gamesDir: *gamesDir, schemaDir: *schemaDir, name: *gameName, id: *id, variant: v,
		notes: *notes, provider: *provider, model: *modelName, attempts: *attempts, bootRounds: *bootRounds, agentImage: agentImage})
	if res != nil && *out != "" {
		raw, _ := json.MarshalIndent(res, "", "  ")
		if werr := os.WriteFile(*out, raw, 0o644); werr != nil && err == nil {
			err = werr
		}
	}
	if err != nil {
		return err
	}
	if !res.Passed {
		return fmt.Errorf("the draft in %s still has problems:\n- %s", res.Dir, strings.Join(res.Problems, "\n- "))
	}
	fmt.Printf("[build] %s booted with the node-agent and is ready for a pull request\n", res.Dir)
	return nil
}

type buildOptions struct {
	gamesDir, schemaDir, name, id string
	variant                       variant
	notes, provider, model        string
	attempts, bootRounds          int
	agentImage                    string
}

// build drafts the template for exactly the option the admin chose: one image (research lists each way to
// run a game as its own option). It never switches to another image; if the chosen one can't be made to
// work, the result says so and the admin can pick a different option.
func build(o buildOptions) (*buildResult, error) {
	for _, image := range o.variant.Images {
		if isSteamCMDImage(image) && o.variant.SteamAppID == "" {
			continue // the SteamCMD image alone runs nothing
		}
		res, err := buildWithImage(o, image)
		if res != nil {
			res.Summary = buildSummary(o, res)
		}
		return res, err
	}
	return nil, errors.New("the variant has no image to build from")
}

// buildWithImage drafts the template for one image: first boot, draft, then boots of the draft with
// failures going back to the model.
func buildWithImage(o buildOptions, image string) (*buildResult, error) {
	res := &buildResult{GameID: o.id, Dir: filepath.Join(o.gamesDir, o.id), Image: image}
	res.Verified = append(res.Verified, o.variant.Verified...)
	steam := isSteamCMDImage(image)

	// 1. First boot of the image untouched: its log, files and settings are the draft's facts
	var report *bootReport
	if steam && o.variant.StartupHint == "" {
		fmt.Printf("[build] no startup command known for Steam app %s; drafting without a first boot\n", o.variant.SteamAppID)
	} else {
		fmt.Printf("[build] first boot of %s\n", image)
		r, err := firstBoot(o.id+"-probe", image, o.variant.SteamAppID, steam, o.variant.StartupHint)
		if err != nil {
			return nil, err
		}
		if why := imageUnusable(r); why != "" {
			fmt.Printf("[build] %s can't be used: %s\n", image, why)
			res.Problems = []string{why}
			return res, nil
		}
		report = r
		res.Verified = append(res.Verified, fmt.Sprintf("first boot of %s: %s", image, r.Outcome))
	}

	// 2. Draft until validation and the image checks pass
	steamApp := ""
	if isSteamCMDImage(res.Image) {
		steamApp = o.variant.SteamAppID
	}
	d, err := newDrafter(draftJob{GamesDir: o.gamesDir, SchemaDir: o.schemaDir, Name: o.name, ID: o.id, Image: res.Image,
		SteamApp: steamApp, Notes: variantNotes(o.variant, o.notes), Report: report, Provider: o.provider, Model: o.model, NoPull: true,
		Docs: sourceText(o.variant.Sources)})
	if err != nil {
		return nil, err
	}
	problems, err := d.refine(o.attempts, nil)
	res.Rounds = d.rounds
	if err != nil {
		return res, err
	}
	if len(problems) > 0 {
		res.Problems = problems
		res.Summary = buildSummary(o, res)
		return res, nil
	}

	// 3. Boot the draft the way nodes run it. A failure is investigated and diagnosed before the model
	// changes anything; a fix that changes nothing rules its cause out
	wantOutside := len(outsideDirs(report)) > 0
	iv := newInvestigator(d.m, o.name, o.gamesDir, o.id, o.agentImage)
	lastFailure := ""
	for boot := 1; boot <= o.bootRounds; boot++ {
		fmt.Printf("[build] boot %d of the draft with the node-agent\n", boot)
		bootProblems, notes, err := bootCheck(o.gamesDir, o.id, o.agentImage, wantOutside)
		if err != nil {
			return res, err
		}
		failure := strings.Join(bootProblems, "\n")
		iv.outcome(len(bootProblems) == 0, lastFailure, failure)
		lastFailure = failure
		if len(bootProblems) == 0 {
			res.Passed = true
			res.Verified = append(res.Verified, notes...)
			break
		}
		fmt.Printf("[build] boot %d failed:\n", boot)
		for _, p := range bootProblems {
			fmt.Println("        - " + firstLine(p))
		}
		res.Problems = bootProblems
		if boot == o.bootRounds {
			break
		}
		diag, err := iv.diagnose(failure)
		if err != nil {
			fmt.Printf("[build] diagnosis failed (%v); sending the failure as it is\n", err)
			diag = &diagnosis{Cause: "unknown", Fix: "find the cause in the server's output", Evidence: failure}
		}
		if iv.ruledOut(diag) {
			res.Problems = append(res.Problems, "the diagnosis came back to a cause an earlier fix ruled out ("+firstLine(diag.Cause)+
				"); the builder stopped rather than guess. See what the builder found")
			break
		}
		iv.record(diag)
		problems, err := d.refine(o.attempts, fixRequest(failure, diag))
		res.Rounds = d.rounds
		if err != nil {
			return res, err
		}
		if len(problems) > 0 {
			res.Problems = problems
			break
		}
	}
	res.Diagnoses = iv.log
	if res.Passed {
		res.Problems = nil
	}
	res.Summary = buildSummary(o, res)
	return res, nil
}

func isSteamCMDImage(image string) bool {
	return image == "cm2network/steamcmd" || strings.HasPrefix(image, "cm2network/steamcmd:")
}

func variantNotes(v variant, admin string) string {
	var parts []string
	if v.Title != "" {
		parts = append(parts, "variant: "+v.Title+" ("+v.Description+")")
	}
	if v.StartupHint != "" {
		parts = append(parts, "documented startup: "+v.StartupHint)
	}
	if len(v.Ports) > 0 {
		parts = append(parts, "documented ports: "+strings.Join(v.Ports, ", "))
	}
	if v.Notes != "" {
		parts = append(parts, v.Notes)
	}
	if admin != "" {
		parts = append(parts, "the admin asked for: "+admin)
	}
	return strings.Join(parts, "; ")
}

// firstBoot runs first-boot and reads back its report.
func firstBoot(name, image, steamApp string, steam bool, startup string) (*bootReport, error) {
	outDir := filepath.Join("firstboot-out", name)
	args := []string{"-image", image, "-out", outDir}
	if steam {
		args = append(args, "-steam-app", steamApp, "-startup", startup)
	}
	if err := runFirstBoot(args); err != nil {
		return nil, err
	}
	return readBootReport(filepath.Join(outDir, "report.json"))
}

// bootCheck deploys the template with the node-agent's BootTest, the same check CI runs, and when the
// game wrote files outside its volume on the first boot, boots it once more to see that it no longer does.
func bootCheck(gamesDir, id, agentImage string, wantOutside bool) (problems, verified []string, err error) {
	if out, err := runCmd("docker", "pull", "-q", agentImage); err != nil {
		return nil, nil, fmt.Errorf("docker pull %s: %v: %s", agentImage, err, out)
	}
	output, passed, problems, err := agentBoot(gamesDir, id, agentImage, false)
	if err != nil || problems != nil {
		return problems, nil, err
	}
	if !passed {
		// The server's own output rarely says it stopped because a setting was empty. Booting once more
		// with the blank ones filled tells for certain whether they are the cause.
		if blank := blankRequiredLooking(gamesDir, id); len(blank) > 0 {
			fmt.Printf("[build] it failed with the defaults; booting again with %s filled to see whether empty settings are the cause\n",
				strings.Join(blank, ", "))
			if _, filledPassed, _, err := agentBoot(gamesDir, id, agentImage, true); err == nil && filledPassed {
				return []string{emptySettingsProblem(blank, bootVerdict(output))}, nil, nil
			}
		}
		return []string{bootFailure(output)}, nil, nil
	}
	verified = append(verified, "boot test with the node-agent: "+bootVerdict(output))

	if wantOutside {
		fmt.Println("[build] first boot wrote saves outside the volume; booting the draft to see that it no longer does")
		r, err := firstBootGame(gamesDir, id)
		if err != nil {
			return nil, nil, err
		}
		if dirs := outsideDirs(r); len(dirs) > 0 {
			return []string{fmt.Sprintf("booting your template, the server still wrote its own files outside the server volume, "+
				"in %s, so your startup command or settings did not move them. Check the exact launch option name and "+
				"syntax this server documents for its save/data folder (a wrong option is usually ignored silently) "+
				"and point it at /server", strings.Join(dirs, ", "))}, nil, nil
		}
		verified = append(verified, "the server keeps its files inside /server")
	}
	return nil, verified, nil
}

// agentBoot runs one boot test with the node-agent's BootTest, with the settings a new server gets, like
// CI. fillBlank also fills blank password-like settings, only to find out whether they are why a draft
// fails. problems is set when the template can't be boot-tested at all.
func agentBoot(gamesDir, id, agentImage string, fillBlank bool) (output string, passed bool, problems []string, err error) {
	payload, err := bootTestPayload(gamesDir, id, fillBlank)
	var missing *missingSecretError
	if errors.As(err, &missing) {
		// The builder has no CI secrets: that's the template's problem to fix, not a reason to stop
		return "", false, []string{"the boot test can't run: " + missing.Error() + ". Remove 'secrets' from " +
			"test.yaml; boot tests run with exactly what a new server gets"}, nil
	}
	if err != nil {
		return "", false, nil, err
	}
	output, passed, err = runAgentBootTest(payload, agentImage)
	return output, passed, nil, err
}

// blankRequiredLooking lists the settings a new server gets empty that look like a server might need a
// value: password-like keys with an empty default and no x-generate.
func blankRequiredLooking(gamesDir, id string) []string {
	g, err := loadMap(filepath.Join(gamesDir, id, "game.yaml"))
	if err != nil {
		return nil
	}
	defaults, _ := g["defaultConfig"].(map[string]any)
	var keys []string
	for key, p := range schemaProperties(g) {
		prop, _ := p.(map[string]any)
		if prop["x-generate"] != nil || !passwordKey.MatchString(key) {
			continue
		}
		if v, ok := defaults[key]; !ok || v == nil || v == "" {
			keys = append(keys, key)
		}
	}
	sort.Strings(keys)
	return keys
}

func emptySettingsProblem(keys []string, verdict string) string {
	return fmt.Sprintf("the server stops when %s is empty, as it is for every new server: booted with your defaults it "+
		"failed (%s), and booted again with a value in %s it ran. A new server must start without the owner typing "+
		"anything: give %s \"x-generate\": {\"type\": \"password\"} in configSchema (the panel then makes a password for "+
		"each server; keep the default \"\"), or a default value that works. Keep the setting so owners can change it",
		strings.Join(keys, ", "), verdict, strings.Join(keys, ", "), strings.Join(keys, ", "))
}

func firstBootGame(gamesDir, id string) (*bootReport, error) {
	outDir := filepath.Join("firstboot-out", id+"-draft")
	if err := runFirstBoot([]string{"-games", gamesDir, "-game", id, "-as-deployed", "-out", outDir}); err != nil {
		return nil, err
	}
	return readBootReport(filepath.Join(outDir, "report.json"))
}

// bootFailure turns BootTest's output into feedback: its verdict and the server's last lines, which hold
// the actual error (an unknown option, a missing file, a port in use).
func bootFailure(output string) string {
	verdict, tail := bootVerdict(output), output
	if i := strings.Index(output, "---- last "); i >= 0 {
		tail = output[i:]
	}
	lines := strings.Split(strings.TrimSpace(tail), "\n")
	if len(lines) > 60 {
		lines = append(lines[:1], lines[len(lines)-59:]...)
	}
	return "booting your template with the node-agent (the real deploy code) failed: " + verdict +
		". It was started with your defaults exactly as a new server gets them: settings left empty stay empty " +
		"(only x-generate fields are filled), so a server that needs a value must get it from a default or " +
		"x-generate. Find the cause in the server's output below and fix the template (startup command, settings, " +
		"ready pattern, memory):\n" + strings.Join(lines, "\n")
}

func bootVerdict(output string) string {
	for _, l := range strings.Split(output, "\n") {
		for _, k := range []string{"[boot-test] FAILED: ", "[boot-test] PASSED: "} {
			if i := strings.Index(l, k); i >= 0 {
				return strings.TrimSpace(l[i+len("[boot-test] "):])
			}
		}
	}
	return "no verdict"
}

func firstLine(s string) string {
	line, _, _ := strings.Cut(s, "\n")
	return line
}

// teeWriter shows the boot as it happens (the worker streams it to the panel) while keeping it for the verdict.
type teeWriter struct{ buf *bytes.Buffer }

func (t *teeWriter) Write(p []byte) (int, error) {
	os.Stdout.Write(p)
	return t.buf.Write(p)
}

// buildSummary is the pull request's description: where the facts came from and what was really checked.
func buildSummary(o buildOptions, res *buildResult) string {
	var b strings.Builder
	fmt.Fprintf(&b, "Drafted by the GBR AI builder. **Review before merging**: check the settings, "+
		"ports and descriptions against the game's documentation.\n\n")
	fmt.Fprintf(&b, "- Game: **%s**", o.name)
	if o.variant.Title != "" {
		fmt.Fprintf(&b, " — %s", o.variant.Title)
	}
	fmt.Fprintf(&b, "\n- Image: `%s`", res.Image)
	if o.variant.SteamAppID != "" && isSteamCMDImage(res.Image) {
		fmt.Fprintf(&b, ", Steam app %s", o.variant.SteamAppID)
	}
	fmt.Fprintf(&b, "\n- Model rounds: %d\n", res.Rounds)
	if len(res.Verified) > 0 {
		b.WriteString("\n**Checked for real**\n")
		for _, v := range res.Verified {
			fmt.Fprintf(&b, "- %s\n", v)
		}
	}
	if len(res.Problems) > 0 {
		b.WriteString("\n**Still open** (the builder could not fix these)\n")
		for _, p := range res.Problems {
			fmt.Fprintf(&b, "- %s\n", firstLine(p))
		}
	}
	if len(res.Diagnoses) > 0 {
		b.WriteString("\n**What the builder found** (after each failed boot)\n")
		for i, a := range res.Diagnoses {
			fmt.Fprintf(&b, "%d. Cause: %s\n   Fix: %s\n   Outcome: %s\n", i+1, firstLine(a.Cause), firstLine(a.Fix), a.Outcome)
		}
	}
	if o.variant.Notes != "" {
		fmt.Fprintf(&b, "\n**Notes from research:** %s\n", o.variant.Notes)
	}
	if len(o.variant.Sources) > 0 {
		b.WriteString("\n**Sources**\n")
		for _, s := range o.variant.Sources {
			fmt.Fprintf(&b, "- %s\n", s)
		}
	}
	return b.String()
}

// sourceText reads the pages research based the variant on, in full, so the drafter can check that every
// launch option the model uses is documented there. Empty (check skipped) without a reader.
func sourceText(sources []string) string {
	reader := os.Getenv("READER_URL")
	if reader == "" || len(sources) == 0 {
		fmt.Println("[build] no research sources to check launch options against (READER_URL or sources missing)")
		return ""
	}
	var b strings.Builder
	read := 0
	for _, s := range sources {
		text, err := readPageLimit(reader, s, 200_000)
		if err != nil {
			fmt.Printf("[build] could not read %s: %v\n", s, err)
			continue
		}
		read++
		b.WriteString(text)
		b.WriteString("\n")
	}
	fmt.Printf("[build] read %d of %d research sources to check launch options against\n", read, len(sources))
	return b.String()
}