// Package runnerbootstrap configures an unmodified, one-shot Gitea Runner to
// consume exactly the task assigned by the controller facade.
package runnerbootstrap

import (
	"encoding/json"
	"errors"
	"fmt"
	"net/url"

	"git.ddupan.top/panxiao81/gitea-dynamic-runner/internal/runnerfacade"
	"git.ddupan.top/panxiao81/gitea-dynamic-runner/internal/taskassignment"
)

const (
	EnvAssignmentID = "CI_ASSIGNMENT_ID"
	EnvCapability   = "CI_RUNNER_CAPABILITY"
	EnvFacadeURL    = "CI_RUNNER_FACADE_URL"
	EnvFacadeID     = "CI_RUNNER_FACADE_SPIFFE_ID"
	EnvSPIFFEID     = "CI_SPIFFE_ID"
	EnvBackend      = "CI_RUNNER_BACKEND"
)

// Bootstrap emits assignment-scoped launch configuration. FacadeURL is the
// controller endpoint reached by the local SPIFFE proxy, not by Runner itself.
type Bootstrap struct {
	Capabilities   runnerfacade.Capabilities
	FacadeURL      string
	FacadeSPIFFEID string
}

func (b Bootstrap) Environment(assignment taskassignment.Assignment) (map[string]string, error) {
	if assignment.ID == "" || assignment.Identity.SPIFFEID == "" || b.FacadeSPIFFEID == "" {
		return nil, errors.New("assignment ID and SPIFFE ID are required")
	}
	parsed, err := url.Parse(b.FacadeURL)
	if err != nil || parsed.Scheme != "https" || parsed.Host == "" {
		return nil, fmt.Errorf("runner facade URL must be an absolute https URL")
	}
	capability := b.Capabilities.Issue(assignment.ID)
	if capability == "" {
		return nil, errors.New("runner capability issuer is not configured")
	}
	return map[string]string{
		EnvAssignmentID: assignment.ID,
		EnvCapability:   capability,
		EnvFacadeURL:    b.FacadeURL,
		EnvFacadeID:     b.FacadeSPIFFEID,
		EnvSPIFFEID:     assignment.Identity.SPIFFEID,
		EnvBackend:      string(assignment.Backend),
	}, nil
}

// Registration mirrors Gitea Runner v3.5.0's registration file schema. ID is
// intentionally zero: the facade authenticates UUID and token and never uses
// the server-issued runner database ID.
type Registration struct {
	Warning   string   `json:"WARNING"`
	ID        int64    `json:"id"`
	UUID      string   `json:"uuid"`
	Name      string   `json:"name"`
	Token     string   `json:"token"`
	Address   string   `json:"address"`
	Labels    []string `json:"labels"`
	Ephemeral bool     `json:"ephemeral"`
}

func RegistrationJSON(assignmentID, capability, localProxyURL string, backend taskassignment.Backend) ([]byte, error) {
	if assignmentID == "" || capability == "" {
		return nil, errors.New("assignment ID and runner capability are required")
	}
	parsed, err := url.Parse(localProxyURL)
	if err != nil || parsed.Scheme != "http" || parsed.Host == "" {
		return nil, errors.New("local runner proxy URL must be an absolute http URL")
	}
	if backend != taskassignment.BackendPod && backend != taskassignment.BackendVM {
		return nil, fmt.Errorf("unsupported runner backend %q", backend)
	}
	registration := Registration{
		Warning: "Generated for one preassigned task by gitea-dynamic-runner.",
		UUID:    assignmentID, Name: assignmentID, Token: capability,
		Address: localProxyURL, Labels: []string{"self-hosted", string(backend)}, Ephemeral: true,
	}
	data, err := json.MarshalIndent(registration, "", "  ")
	if err != nil {
		return nil, err
	}
	return append(data, '\n'), nil
}