package pi

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

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

// Runner is the narrow, shell-free command boundary shared with thothctl.
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
	}
	if _, err := Status(ctx, runner); err != nil {
		return err
	}
	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 nil
}

// Test performs the pre-Task-8 composite smoke through core's private loopback endpoint.
func Test(ctx context.Context, runner Runner) error {
	if _, err := Status(ctx, runner); err != nil {
		return err
	}
	for _, path := range []string{"health", "models", "settings"} {
		result, err := runCompose(ctx, runner, "exec", "-T", "core", "curl", "-fsS", "http://127.0.0.1:8787/"+path)
		if err != nil {
			return commandError("Pi smoke check", result, err)
		}
		var payload any
		if err := json.Unmarshal([]byte(result.Stdout), &payload); err != nil {
			return fmt.Errorf("Pi smoke check returned invalid %s response", path)
		}
		if _, ok := payload.(map[string]any); !ok {
			return fmt.Errorf("Pi smoke check returned invalid %s response", path)
		}
	}
	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 struct {
		Services map[string]struct {
			Image       string         `json:"image"`
			Environment map[string]any `json:"environment"`
		} `json:"services"`
	}
	if err := json.Unmarshal([]byte(result.Stdout), &document); err != nil {
		return Image{}, errors.New("Compose returned invalid rendered configuration")
	}
	core, exists := document.Services["core"]
	if !exists || core.Image == "" {
		return Image{}, errors.New("rendered Compose configuration has no core image")
	}
	endpoint, exists := core.Environment["THT_LLM_URL"].(string)
	if !exists || strings.TrimSpace(endpoint) == "" {
		return Image{}, errors.New("THT_LLM_URL must be configured before Pi lifecycle operations")
	}
	digest := sha256.Sum256([]byte(result.Stdout))
	return Image{Reference: core.Image, 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 }