package pi

import (
	"context"
	"crypto/sha256"
	"encoding/json"
	"errors"
	"fmt"
	"io"
	"strings"

	"github.com/aritmolab/thothii/tools/tht/internal/compose"
)

// Runner is the narrow, shell-free command boundary shared with tht.
type Runner interface {
	Run(context.Context, []string, io.Reader) (compose.Result, error)
}

// Status reports the image-bundled Pi version without using a host Pi executable.
func Status(ctx context.Context, runner Runner) (string, error) {
	result, err := runCompose(ctx, runner, "exec", "-T", "core", "pi", "--version")
	if err != nil {
		return "", commandError("Pi version check", result, err)
	}
	version := strings.TrimSpace(result.Stdout)
	if version == "" {
		return "", errors.New("Pi version check returned no version")
	}
	return version, nil
}

// Doctor verifies the installation-side invariants Pi needs before an update.
func Doctor(ctx context.Context, runner Runner) error {
	if _, err := renderedCore(ctx, runner); err != nil {
		return err
	}
	actual, err := Status(ctx, runner)
	if err != nil {
		return err
	}
	expected, label, err := expectedVersions(ctx, runner)
	if err != nil {
		return err
	}
	if actual != expected || actual != label {
		return errors.New("Pi version does not match the image PI_VERSION and io.thothii.pi.version contract")
	}
	for _, check := range [][]string{
		{"exec", "-T", "core", "sh", "-ceu", "test -w /home/thoth/.pi"},
		{"exec", "-T", "core", "sh", "-ceu", "test -r /home/thoth/.pi/agent/auth.json"},
		{"exec", "-T", "core", "curl", "-fsS", "http://127.0.0.1:8787/health"},
	} {
		result, err := runCompose(ctx, runner, check...)
		if err != nil {
			return commandError("Pi preflight check", result, err)
		}
	}
	return Test(ctx, runner)
}

func expectedVersions(ctx context.Context, runner Runner) (string, string, error) {
	environment, err := runCompose(ctx, runner, "exec", "-T", "core", "sh", "-ceu", `printf '%s\n' "${PI_VERSION:-}"`)
	if err != nil {
		return "", "", commandError("Pi expected-version check", environment, err)
	}
	container, err := runCompose(ctx, runner, "ps", "-q", "core")
	if err != nil || strings.TrimSpace(container.Stdout) == "" {
		return "", "", commandError("Pi image-label check", container, err)
	}
	label, err := runner.Run(ctx, []string{"inspect", "--format", `{{ index .Config.Labels "io.thothii.pi.version" }}`, strings.TrimSpace(container.Stdout)}, nil)
	if err != nil {
		return "", "", commandError("Pi image-label check", label, err)
	}
	expectedValue, labelValue := strings.TrimSpace(environment.Stdout), strings.TrimSpace(label.Stdout)
	if expectedValue == "" || labelValue == "" {
		return "", "", errors.New("Pi image expected-version contract is empty")
	}
	return expectedValue, labelValue, nil
}

// Test retains the direct image-version signal, then invokes the same Pi management service via a
// scoped core-side command. No HTTP principal or privileged header exists on this path.
func Test(ctx context.Context, runner Runner) error {
	if _, err := Status(ctx, runner); err != nil {
		return err
	}
	smoke, err := runCompose(ctx, runner, "exec", "-T", "core", "node", "/app/backend/dist/operator-command.js", "pi-test")
	if err != nil {
		return commandError("Pi smoke check", smoke, err)
	}
	var smokePayload struct {
		Ready bool `json:"ready"`
	}
	if json.Unmarshal([]byte(smoke.Stdout), &smokePayload) != nil || !smokePayload.Ready {
		return errors.New("Pi smoke response is not ready")
	}
	return nil
}

func renderedCore(ctx context.Context, runner Runner) (Image, error) {
	result, err := runCompose(ctx, runner, "config", "--format", "json")
	if err != nil {
		return Image{}, commandError("Compose configuration check", result, err)
	}
	var document map[string]any
	if err := json.Unmarshal([]byte(result.Stdout), &document); err != nil {
		return Image{}, errors.New("Compose returned invalid rendered configuration")
	}
	services, ok := document["services"].(map[string]any)
	if !ok {
		return Image{}, errors.New("rendered Compose configuration has no services")
	}
	core, ok := services["core"].(map[string]any)
	reference, _ := core["image"].(string)
	if !ok || reference == "" {
		return Image{}, errors.New("rendered Compose configuration has no core image")
	}
	environment, _ := core["environment"].(map[string]any)
	endpoint, exists := environment["THT_LLM_URL"].(string)
	if !exists || strings.TrimSpace(endpoint) == "" {
		return Image{}, errors.New("THT_LLM_URL must be configured before Pi lifecycle operations")
	}
	// Lifecycle overrides intentionally replace only core.image. Normalize that field so the
	// non-secret configuration digest continues to detect endpoint/mount/configuration drift.
	core["image"] = "<lifecycle-image>"
	normalized, err := json.Marshal(document)
	if err != nil {
		return Image{}, errors.New("Compose configuration could not be normalized")
	}
	digest := sha256.Sum256(normalized)
	return Image{Reference: reference, ConfigurationSHA: fmt.Sprintf("%x", digest[:])}, nil
}

func runCompose(ctx context.Context, runner Runner, args ...string) (compose.Result, error) {
	return runner.Run(ctx, append([]string{"compose"}, args...), nil)
}

func commandError(label string, result compose.Result, err error) error {
	if result.ExitCode != 0 {
		return commandFailure{message: fmt.Sprintf("%s failed (exit %d)", label, result.ExitCode), exitCode: result.ExitCode}
	}
	return commandFailure{message: fmt.Sprintf("%s failed", label)}
}

type commandFailure struct {
	message  string
	exitCode int
}

func (e commandFailure) Error() string { return e.message }

// ExitCode exposes a Docker child exit code without exposing its output.
func (e commandFailure) ExitCode() int { return e.exitCode }