package node

import (
	"context"
	_ "embed"
	"encoding/json"
	"io"
	"os"
	"os/exec"
	"time"
)

//go:embed environment-profile.json
var environmentProfile []byte

type EnvironmentRun struct {
	Schema          string            `json:"schema"`
	ProfileRevision string            `json:"profile_revision"`
	RunID           string            `json:"run_id"`
	State           string            `json:"state"`
	StartedAt       float64           `json:"started_at"`
	UpdatedAt       float64           `json:"updated_at"`
	Steps           []EnvironmentStep `json:"steps"`
}
type EnvironmentStep struct {
	ID     string `json:"id"`
	State  string `json:"state"`
	Detail string `json:"detail"`
}
type EnvironmentStatus struct {
	Profile   json.RawMessage `json:"profile"`
	Run       *EnvironmentRun `json:"run"`
	Available bool            `json:"available"`
}

func ReadEnvironment() EnvironmentStatus {
	result := readEnvironmentFile("/var/lib/mission-core-node-environment/last-run.json")
	if result.Run != nil && result.Run.State == "running" {
		ctx, cancel := context.WithTimeout(context.Background(), 2*time.Second)
		defer cancel()
		state, err := exec.CommandContext(ctx, "/usr/bin/systemctl", "show", "--property=ActiveState", "--value", "mission-core-node-environment.service").Output()
		if err != nil || (string(state) != "activating\n" && string(state) != "active\n") {
			// A stopped job/reboot cannot leave yesterday's spinner running.
			result.Run.State = "interrupted"
		}
	}
	return result
}

func readEnvironmentFile(path string) EnvironmentStatus {
	result := EnvironmentStatus{Profile: json.RawMessage(environmentProfile), Available: true}
	f, err := os.Open(path)
	if os.IsNotExist(err) {
		return result
	}
	if err != nil {
		result.Available = false
		return result
	}
	defer f.Close()
	info, err := f.Stat()
	if err != nil || !info.Mode().IsRegular() || info.Size() > 32768 {
		result.Available = false
		return result
	}
	var run EnvironmentRun
	decoder := json.NewDecoder(io.LimitReader(f, 32769))
	if decoder.Decode(&run) != nil || decoder.Decode(new(any)) != io.EOF || !validEnvironmentRun(run) {
		result.Available = false
		return result
	}
	result.Run = &run
	return result
}

// Invalid or inconsistent progress cannot turn a failed setup into green UI.
func validEnvironmentRun(run EnvironmentRun) bool {
	if run.Schema != "missioncore.node.environment/v1" || run.RunID == "" || len(run.RunID) > 64 || len(run.Steps) == 0 || len(run.Steps) > 32 || run.ProfileRevision == "" {
		return false
	}
	if run.State != "running" && run.State != "complete" && run.State != "error" {
		return false
	}
	seen := map[string]bool{}
	for _, step := range run.Steps {
		if step.ID == "" || len(step.ID) > 64 || seen[step.ID] || len(step.Detail) > 4096 {
			return false
		}
		seen[step.ID] = true
		switch step.State {
		case "pending", "running", "complete", "error", "blocked":
		default:
			return false
		}
		if run.State == "complete" && step.State != "complete" {
			return false
		}
	}
	return true
}