package httpapi

import (
	"context"
	"net/http"
	"strconv"
	"strings"

	"data-terminal-cloud/internal/device"
	"data-terminal-cloud/internal/deviceauth"
	"data-terminal-cloud/internal/saas"
)

type DeviceCommandService interface {
	PullCommands(context.Context, deviceauth.Identity, int) ([]device.Command, error)
	AcknowledgeCommand(context.Context, deviceauth.Identity, string, device.CommandAcknowledgement) (device.Command, error)
}

func PullDeviceCommandsHandler(service DeviceCommandService) http.Handler {
	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		id, ok := deviceauth.FromContext(r.Context())
		if !ok {
			WriteError(w, r, http.StatusUnauthorized, "DEVICE_AUTHENTICATION_FAILED", "设备身份验证失败")
			return
		}
		limit, _ := strconv.Atoi(r.URL.Query().Get("limit"))
		items, err := service.PullCommands(r.Context(), id, limit)
		if err != nil {
			WriteAPIError(w, r, http.StatusServiceUnavailable, Error{Code: "DEVICE_COMMANDS_UNAVAILABLE", Message: "暂时无法读取设备命令", Retryable: true})
			return
		}
		WriteJSON(w, r, http.StatusOK, map[string]any{"items": items})
	})
}

func AcknowledgeDeviceCommandHandler(service DeviceCommandService) http.Handler {
	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		id, ok := deviceauth.FromContext(r.Context())
		if !ok {
			WriteError(w, r, http.StatusUnauthorized, "DEVICE_AUTHENTICATION_FAILED", "设备身份验证失败")
			return
		}
		var input struct {
			Status        string         `json:"status"`
			ResultSummary map[string]any `json:"result_summary"`
		}
		if !decodeWebJSON(w, r, &input, "设备命令回执不正确") {
			return
		}
		input.Status = strings.ToUpper(strings.TrimSpace(input.Status))
		if input.Status != "ACKNOWLEDGED" && input.Status != "SUCCEEDED" && input.Status != "FAILED" {
			writeValidation(w, r, "设备命令回执不正确", FieldError{Field: "status", Message: "必须为ACKNOWLEDGED、SUCCEEDED或FAILED"})
			return
		}
		if input.ResultSummary == nil {
			input.ResultSummary = map[string]any{}
		}
		item, err := service.AcknowledgeCommand(r.Context(), id, r.PathValue("id"), device.CommandAcknowledgement{Status: input.Status, ResultSummary: input.ResultSummary})
		if err != nil {
			WriteError(w, r, http.StatusConflict, "DEVICE_COMMAND_STATE_CONFLICT", "命令不存在、已过期或状态不允许回执")
			return
		}
		WriteJSON(w, r, http.StatusOK, item)
	})
}

func ListDeviceCommandsHandler(service *saas.Service) http.Handler {
	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		p, ok := resourcePrincipal(w, r, "id")
		if !ok {
			return
		}
		items, err := service.ListDeviceCommands(r.Context(), p, r.PathValue("id"))
		if err != nil {
			writeSaaSError(w, r, err)
			return
		}
		WriteJSON(w, r, http.StatusOK, map[string]any{"items": items})
	})
}

func CreateDeviceCommandHandler(service *saas.Service) http.Handler {
	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		p, ok := resourcePrincipal(w, r, "id")
		if !ok {
			return
		}
		key := strings.TrimSpace(r.Header.Get("Idempotency-Key"))
		if len(key) < 16 || len(key) > 128 {
			writeValidation(w, r, "缺少有效的重复请求识别码", FieldError{Field: "Idempotency-Key", Message: "长度必须为16至128字符"})
			return
		}
		var input struct {
			Type         string         `json:"type"`
			Payload      map[string]any `json:"payload"`
			ExpiresInSec int            `json:"expires_in_sec"`
		}
		if !decodeWebJSON(w, r, &input, "设备命令参数不正确") {
			return
		}
		input.Type = strings.TrimSpace(input.Type)
		if input.Type != "apply_config" && input.Type != "reboot" && input.Type != "diagnostics" && input.Type != "firmware_update" {
			writeValidation(w, r, "设备命令参数不正确", FieldError{Field: "type", Message: "命令类型不受支持"})
			return
		}
		if input.ExpiresInSec < 30 || input.ExpiresInSec > 86400 {
			writeValidation(w, r, "设备命令参数不正确", FieldError{Field: "expires_in_sec", Message: "必须为30至86400秒"})
			return
		}
		if input.Payload == nil {
			input.Payload = map[string]any{}
		}
		item, created, err := service.CreateDeviceCommand(r.Context(), p, r.PathValue("id"), key, RequestID(r.Context()), input.Type, input.Payload, input.ExpiresInSec)
		if err != nil {
			writeSaaSError(w, r, err)
			return
		}
		status := http.StatusAccepted
		if !created {
			status = http.StatusOK
			w.Header().Set("Idempotency-Replayed", "true")
		}
		WriteJSON(w, r, status, item)
	})
}