// Command fluid is the FLUID operator CLI.
//
// It reads and writes the evidence store directly rather than going through the
// control-plane API, so that an operator can still inspect an interface's
// history when the control plane is down. Auditability must not depend on the
// availability of the thing being audited.
package main

import (
	"context"
	"errors"
	"flag"
	"fmt"
	"os"
	"path/filepath"
	"strings"
)

const usage = `fluid — FLUID operator CLI

Usage:
  fluid [--store PATH] [--interface ID] <command> [arguments]

Commands:
  intent put       Record an interface evolution intent version
  intent activate  Make a recorded version the governing intent
  intent show      Show the active or a named intent version
  revision publish Publish a signed revision descriptor
  revision list    List published revisions
  revision show    Show one revision descriptor
  policy put       Install a routing policy
  policy show      Show the current routing policy
  events           Show audit events
  telemetry        Show recorded telemetry
  audit trace      Reconstruct the history behind a revision

Global flags:
  --store PATH     Evidence store path (default $FLUID_STORE or ./fluid.db)
  --interface ID   Interface identifier (default $FLUID_INTERFACE)
`

func main() {
	if err := run(os.Args[1:]); err != nil {
		if errors.Is(err, flag.ErrHelp) {
			os.Exit(0)
		}
		fmt.Fprintln(os.Stderr, "fluid:", err)
		os.Exit(1)
	}
}

type globals struct {
	store     string
	iface     string
	remaining []string
}

func parseGlobals(args []string) (globals, error) {
	g := globals{
		store: envOr("FLUID_STORE", "fluid.db"),
		iface: os.Getenv("FLUID_INTERFACE"),
	}

	i := 0
	for i < len(args) {
		switch args[i] {
		case "--store":
			if i+1 >= len(args) {
				return g, errors.New("--store needs a value")
			}
			g.store, i = args[i+1], i+2
		case "--interface":
			if i+1 >= len(args) {
				return g, errors.New("--interface needs a value")
			}
			g.iface, i = args[i+1], i+2
		case "-h", "--help", "help":
			fmt.Print(usage)
			return g, flag.ErrHelp
		default:
			if strings.HasPrefix(args[i], "--") {
				return g, fmt.Errorf("unknown global flag %q", args[i])
			}
			g.remaining = args[i:]
			return g, nil
		}
	}
	g.remaining = nil
	return g, nil
}

func run(args []string) error {
	g, err := parseGlobals(args)
	if err != nil {
		return err
	}
	if len(g.remaining) == 0 {
		fmt.Print(usage)
		return nil
	}

	ctx := context.Background()
	cmd, rest := g.remaining[0], g.remaining[1:]

	switch cmd {
	case "intent":
		return runIntent(ctx, g, rest)
	case "revision":
		return runRevision(ctx, g, rest)
	case "policy":
		return runPolicy(ctx, g, rest)
	case "events":
		return runEvents(ctx, g, rest)
	case "telemetry":
		return runTelemetry(ctx, g, rest)
	case "audit":
		return runAudit(ctx, g, rest)
	default:
		return fmt.Errorf("unknown command %q (try `fluid help`)", cmd)
	}
}

func envOr(key, fallback string) string {
	if v := os.Getenv(key); v != "" {
		return v
	}
	return fallback
}

// requireInterface fails clearly rather than silently operating on the wrong
// interface's history.
func (g globals) requireInterface() (string, error) {
	if g.iface == "" {
		return "", errors.New("no interface selected: pass --interface or set FLUID_INTERFACE")
	}
	return g.iface, nil
}

func (g globals) storePath() string {
	if abs, err := filepath.Abs(g.store); err == nil {
		return abs
	}
	return g.store
}