package main

import (
	"context"
	"errors"
	"flag"
	"fmt"
	"os"
	"strings"

	"github.com/tegwick/fluid-telegram/internal/avatar"
	"github.com/tegwick/fluid-telegram/internal/plan"
	"github.com/tegwick/fluid-telegram/internal/secrets"
	"github.com/tegwick/fluid-telegram/internal/spec"
	"github.com/tegwick/fluid-telegram/internal/state"
	tgc "github.com/tegwick/fluid-telegram/internal/tg"
)

// cmdPreflight exercises everything up to the point of contacting Telegram.
//
// It exists because the expensive failures in this tool all happen after a
// phone number has been spent and a conversation has started. Spec, OpenBao
// wiring, credentials, the avatar and the plan can all be wrong in ways that are
// free to discover beforehand, and this finds them in one run.
//
// It never writes and never contacts Telegram.
func cmdPreflight(args []string) error {
	fs := flag.NewFlagSet("preflight", flag.ExitOnError)
	specPath := fs.String("spec", "", "path to the presence spec")
	root := fs.String("root", ".", "repo root holding presence/resolved/")
	fs.Parse(args)
	if *specPath == "" {
		return errors.New("--spec is required")
	}

	ctx := context.Background()
	var failed, warned int
	ok := func(format string, a ...any) { fmt.Printf("  ok    "+format+"\n", a...) }
	warn := func(format string, a ...any) { warned++; fmt.Printf("  warn  "+format+"\n", a...) }
	bad := func(format string, a ...any) { failed++; fmt.Printf("  FAIL  "+format+"\n", a...) }

	fmt.Print("preflight -- nothing is written and telegram is not contacted\n\n")

	// 1. The spec.
	sp, digest, err := spec.Load(*specPath)
	if err != nil {
		bad("spec: %v", err)
		return report(failed, warned)
	}
	ok("spec loads and validates (campaign %q, %s)", sp.Campaign, shortDigest(digest))

	// 2. The avatar, before any conversation could be left half-finished.
	switch img, err := avatar.Load(*specPath, sp.Bot.Avatar); {
	case sp.Bot.Avatar == "":
		warn("no avatar declared; the bot will have no picture")
	case errors.Is(err, avatar.ErrMissing):
		warn("avatar declared but missing: %s", sp.Bot.Avatar)
	case err != nil:
		bad("avatar: %v", err)
	default:
		ok("avatar %s (%dx%d, %d KiB)", sp.Bot.Avatar, img.Width, img.Height, img.Bytes/1024)
		if note := img.CropNote(); note != "" {
			warn("avatar %s", note)
		}
	}

	// 3. OpenBao: configured, reachable, and the token actually works. A token
	// that is merely present is not a token that can read.
	store, err := secrets.NewFromEnv(sp.Campaign)
	if err != nil {
		bad("openbao: %v", err)
		return report(failed, warned)
	}
	ok("openbao configured (%s)", os.Getenv("BAO_ADDR"))

	appFields, found, err := store.Get(ctx, secrets.KeyOperatorApp)
	switch {
	case err != nil:
		if strings.Contains(err.Error(), "403") {
			bad("openbao rejected the token (403). If `bao token lookup` also fails,\n"+
				"        the token has expired -- run `bao login`. If lookup succeeds,\n"+
				"        the token lacks a policy for %s", store.Ref(secrets.KeyOperatorApp))
		} else {
			bad("openbao unreachable: %v", err)
		}
	case !found:
		bad("no app credentials at %s\n        write them with:\n"+
			"          bao kv put %s api_id=<n> api_hash=<hash>\n"+
			"        see docs/seeding-runbook.md step 2",
			store.Ref(secrets.KeyOperatorApp), kvPath(store))
	default:
		if _, err := tgc.LoadCredentials(ctx, store); err != nil {
			bad("app credentials are present but unusable: %v", err)
		} else {
			ok("app credentials readable (api_id %s...)", prefix(appFields["api_id"], 3))
		}
	}

	// 4. The session. Absent is the expected state before the first bootstrap,
	// so it is reported rather than failed.
	if _, found, err := store.Get(ctx, secrets.KeyOperatorSession); err != nil {
		bad("session check: %v", err)
	} else if !found {
		warn("no operator session yet -- run `provision session bootstrap --campaign %s`", sp.Campaign)
	} else {
		ok("operator session present (validity is only knowable by connecting)")
	}

	// 5. The salt, which must never be regenerated once it exists.
	if _, found, err := store.Get(ctx, secrets.KeyRedactionSalt); err == nil {
		if found {
			ok("redaction salt already present; apply will not touch it")
		} else {
			ok("no redaction salt yet; apply will create one, once")
		}
	}

	// 6. The plan that would result.
	rs, err := state.Load(state.Path(*root, sp.Campaign))
	if err != nil {
		bad("resolved state: %v", err)
		return report(failed, warned)
	}
	p, err := plan.Compute(*specPath, sp, digest, rs, offlineLive{})
	if err != nil {
		bad("plan: %v", err)
		return report(failed, warned)
	}
	if p.Blocked() {
		bad("the resulting plan is blocked")
	} else {
		ok("plan computes cleanly")
	}

	fmt.Printf("\n%s\n", indent(p.Render()))
	fmt.Println("note: computed offline, so nothing was observed live.")
	return report(failed, warned)
}

func report(failed, warned int) error {
	fmt.Println()
	if failed > 0 {
		return fmt.Errorf("%d check(s) failed, %d warning(s)", failed, warned)
	}
	fmt.Printf("preflight passed with %d warning(s)\n", warned)
	return nil
}

func kvPath(s *secrets.Store) string {
	// Ref renders as bao:<mount>/<prefix>/<key>; the bao CLI wants it without
	// the scheme, and without the KV v2 "data" segment the HTTP API needs.
	return strings.TrimPrefix(s.Ref(secrets.KeyOperatorApp), "bao:")
}

func prefix(s string, n int) string {
	if len(s) <= n {
		return s
	}
	return s[:n]
}

func indent(s string) string {
	var b strings.Builder
	for _, line := range strings.Split(strings.TrimRight(s, "\n"), "\n") {
		b.WriteString("  " + line + "\n")
	}
	return b.String()
}

func shortDigest(d string) string {
	d = strings.TrimPrefix(d, "sha256:")
	if len(d) > 12 {
		d = d[:12]
	}
	return "sha256:" + d
}