package backend

import (
	"apiserver/models"
	"time"
)

// JobID bit layout constants — mirrors src/include/config.h.
//
//	|63     62|61        56|55       52|51         20|19      15|14          0|
//	|  TAG   | CLUSTER_ID | APISERVER_ID| TIMESTAMP  | SEQ_HIGH  | ARRAY_IDX  |
//	| 2 bits | 6 bits     | 4 bits      | 32 bits    | 15 bits   | 15 bits     |
const (
	nTagBits          = 2
	tagShift          = 62
	nClusterIDBits    = 6
	clusterIDShift    = 56
	nApiserverIDBits  = 4
	apiserverIDShift  = 52
	nTimestampBits    = 32
	timestampShift    = 20
	nArrayIdxBits     = 15
	sequenceHighShift = 15   // mirrors SEQUENCE_HIGH_SHIFT in config.h
	nSequenceBits     = 30   // mirrors N_SEQUENCE_BITS in config.h
	tagJobArray       = 0x01 // mirrors TAG_JOB_ARRAY in config.h
)

// extractBits extracts a bit field from id at the given shift position.
// Mirrors EXTRACT_BITS(id, shift, bits) in src/include/utils.h.
func extractBits(id uint64, shift, bits int) uint64 {
	mask := uint64((1 << bits) - 1)
	return (id >> shift) & mask
}

// extractIDTag extracts the 2-bit tag field (bits 62-63).
// Mirrors EXTRACT_ID_TAG in src/include/utils.h.
func extractIDTag(id uint64) uint64 {
	return extractBits(id, tagShift, nTagBits)
}

// ExtractArrayBaseID extracts the base (family) job ID from a 64-bit encoded
// jobid. Mirrors C's array_jobid() in src/lib/utils.c and EXTRACT_ARRAY_BASEID
// in src/include/utils.h.
//   - For non-array jobs (tag=0x00): returns id unchanged.
//   - For array children (tag=0x01): returns the shared base ID (tag=0, idx=0).
func ExtractArrayBaseID(id uint64) uint64 {
	if extractIDTag(id) == 0x00 {
		return id
	}
	clusterID := extractBits(id, clusterIDShift, nClusterIDBits)
	apiserverID := extractBits(id, apiserverIDShift, nApiserverIDBits)
	timestamp := extractBits(id, timestampShift, nTimestampBits)
	// EXTRACT_ARRAY_JOB: high bits of sequence (mirrors config.h SEQUENCE_HIGH_SHIFT)
	arrayJob := extractBits(id, sequenceHighShift, nSequenceBits-nArrayIdxBits) << sequenceHighShift
	return (clusterID << clusterIDShift) |
		(apiserverID << apiserverIDShift) |
		(timestamp << timestampShift) |
		arrayJob // tag=0, idx=0
}

// ExtractArrayIdx extracts the array index from a 64-bit encoded jobid.
// Mirrors C's array_idx() in src/lib/utils.c and EXTRACT_ARRAY_IDX in
// src/include/utils.h.
// Returns 0 for non-array jobs (tag=0x00).
func ExtractArrayIdx(id uint64) int {
	if extractIDTag(id) == 0x00 {
		return 0
	}
	return int(extractBits(id, 0, nArrayIdxBits))
}

// IsArrayJob reports whether the 64-bit encoded jobid belongs to an array job
// (tag == TAG_JOB_ARRAY, 0x01). Returns false for non-array jobs (tag=0x00).
func IsArrayJob(id uint64) bool {
	return extractIDTag(id) == tagJobArray
}

// rawStartInfo mirrors the C job_startinfo_t fields used by the Go model.
type rawStartInfo struct {
	cmdline    string
	launchType string
	preExec    string
	postExec   string
	execHome   string
	execCWD    string
	execUser   string
}

// rawSubmitData mirrors the C job_submit_data_t fields used by the Go model.
type rawSubmitData struct {
	queue       string
	user        string
	jobName     string
	projectName string
	userGroup   string
	jobDesc     string
	resReq      string
	minTasks    int
	maxTasks    int
	startInfo   *rawStartInfo
}

// rawJobData mirrors the C xce_job_t fields used by the Go model.
type rawJobData struct {
	jobID      int64
	state      int
	runTime    int
	subTime    int64
	queueTime  int64
	startTime  int64
	finishTime int64
	submit     *rawSubmitData
}

// rawWorkerData mirrors the C xce_worker_t fields used by the Go model.
type rawWorkerData struct {
	name      string
	status    int
	hasAttrs  bool
	hostType  string
	hostModel string
	cpuFactor float64
	maxCPUs   int
	maxMem    int
	maxSwap   int
	maxTmp    int
	nDisks    int
}

// rawQueueData mirrors the C xce_queue_t fields used by the Go model.
type rawQueueData struct {
	name     string
	status   int
	priority int
}

// rawResourceData mirrors the C xce_resource_t fields used by the Go model.
type rawResourceData struct {
	name     string
	desc     string
	valType  int
	ordType  int
	flags    int
	interval int
}

// rawJobToModel maps a rawJobData to a models.JobInfo.
// This pure-Go function contains the field-mapping logic and is tested without CGO.
func rawJobToModel(r rawJobData) *models.JobInfo {
	raw := uint64(r.jobID)
	info := &models.JobInfo{
		Unique_JobID: r.jobID,
		JobID:        int64(ExtractArrayBaseID(raw)),
		ArrayIdx:     ExtractArrayIdx(raw),
		JobStatus:    r.state,
		RunTime:      r.runTime,
	}
	if r.submit != nil {
		s := r.submit
		info.QueueName = s.queue
		info.SubmitUser = s.user
		info.JobName = s.jobName
		info.ProjectName = s.projectName
		info.UserGroup = s.userGroup
		info.JobDescription = s.jobDesc
		info.ResReq = s.resReq
		info.NumProcessors = s.minTasks
		info.MaxNumProcessors = s.maxTasks
		if s.startInfo != nil {
			si := s.startInfo
			info.Command = si.cmdline
			info.LaunchType = si.launchType
			info.PreExecCmd = si.preExec
			info.PostExecCmd = si.postExec
			info.ExecHome = si.execHome
			info.ExecCWD = si.execCWD
			info.ExecUser = si.execUser
		}
	}
	if r.subTime > 0 {
		info.SubmitTime = time.Unix(r.subTime, 0)
	}
	if r.queueTime > 0 {
		info.QueueTime = time.Unix(r.queueTime, 0)
	}
	if r.startTime > 0 {
		info.StartTime = time.Unix(r.startTime, 0)
	}
	if r.finishTime > 0 {
		info.EndTime = time.Unix(r.finishTime, 0)
	}
	return info
}

// rawWorkerToModel maps a rawWorkerData to a models.HostInfo.
func rawWorkerToModel(r rawWorkerData) *models.HostInfo {
	info := &models.HostInfo{
		HostName:   r.name,
		HostStatus: r.status,
	}
	if r.hasAttrs {
		info.HostType = r.hostType
		info.HostModel = r.hostModel
		info.CPUFactor = r.cpuFactor
		info.NumCPUs = r.maxCPUs
		info.MaxMem = r.maxMem
		info.MaxSwap = r.maxSwap
		info.MaxTmp = r.maxTmp
		info.NumDisk = r.nDisks
	}
	return info
}

// rawQueueToModel maps a rawQueueData to a models.QueueInfo.
func rawQueueToModel(r rawQueueData) *models.QueueInfo {
	return &models.QueueInfo{
		QueueName:   r.name,
		QueueStatus: r.status,
		Priority:    r.priority,
	}
}

// rawResourceToModel maps a rawResourceData to a models.ResourceDefinitionInfo.
func rawResourceToModel(r rawResourceData) *models.ResourceDefinitionInfo {
	return &models.ResourceDefinitionInfo{
		ResourceName: r.name,
		Description:  r.desc,
		ValueType:    r.valType,
		OrderType:    r.ordType,
		Flag:         r.flags,
		Interval:     r.interval,
	}
}

// rawHostConfigData mirrors the C xce_hostconfig_t fields used by the Go model.
// Only fields that map to models.HostInfo are included:
//   - name → HostName, hostmodel → HostModel, hosttype → HostType, mxj → MaxSlot
//
// resources (xce_config_t**) and thresholds (xce_res_threshold_t**) have no HostInfo field and are excluded.
// dispatchwindow (xce_timewindow_config_t*) is deferred — DisptWindow is left as empty string.
type rawHostConfigData struct {
	name      string
	hostmodel string
	hosttype  string
	mxj       int
}

// rawHostConfigToModel maps a rawHostConfigData to a models.HostInfo.
// Config-sourced fields only; worker-sourced fields remain zero.
func rawHostConfigToModel(r rawHostConfigData) *models.HostInfo {
	return &models.HostInfo{
		HostName:  r.name,
		HostModel: r.hostmodel,
		HostType:  r.hosttype,
		MaxSlot:   r.mxj,
		// TODO(dispatchwindow): xce_hostconfig_t.dispatchwindow is xce_timewindow_config_t*
		// (nsegs int + segs[] with open/close time fields). Serializing it requires a Go
		// mirror struct and json.Marshal. Deferred: no API endpoint currently consumes
		// DisptWindow. Implement when /xce/v1/hosts returns dispatch window data.
	}
}

// rawResvalData mirrors the C xce_resval_t fields used by the Go model.
// IsDynamic is always true for push-sourced values (controller sends live measurements).
type rawResvalData struct {
	name     string
	host     string
	valWhich int // mirrors C xce_val_t.which (Value_u_* discriminant)
	i32      int32
	i64      int64
	u32      uint32
	u64      uint64
	fval     float64
	sval     string
	bval     bool
	valNil   bool // true when the C xce_val_t* was NULL
}

// rawResvalToDistribution maps a rawResvalData to a models.ResourceDistributionInfo.
// Returns nil when valNil is true (C val pointer was NULL) or when valWhich
// is an unknown discriminant — callers should skip nil results.
func rawResvalToDistribution(r rawResvalData) *models.ResourceDistributionInfo {
	rd := &models.ResourceDistributionInfo{
		ResourceName: r.name,
		Location:     r.host,
		IsDynamic:    true, // resource values pushed from workers are always dynamic
	}
	if r.valNil {
		return nil
	}
	switch r.valWhich {
	case 0: // Value_u_ivalue32
		rd.ValueType = int(models.NUMERIC)
		rd.NumericValue = float64(r.i32)
	case 2: // Value_u_ivalue64
		rd.ValueType = int(models.NUMERIC)
		rd.NumericValue = float64(r.i64)
	case 1: // Value_u_uvalue32
		rd.ValueType = int(models.NUMERIC)
		rd.NumericValue = float64(r.u32)
	case 3: // Value_u_uvalue64
		rd.ValueType = int(models.NUMERIC)
		rd.NumericValue = float64(r.u64)
	case 5: // Value_u_fvalue
		rd.ValueType = int(models.NUMERIC)
		rd.NumericValue = r.fval
	case 4: // Value_u_svalue
		rd.ValueType = int(models.STRING)
		rd.StringValue = r.sval
	case 6: // Value_u_bvalue
		rd.ValueType = int(models.BOOLEAN)
		rd.BooleanValue = r.bval
	default:
		return nil
	}
	return rd
}

// rawClusterData mirrors the C cluster_config_t fields used by the Go model.
// Only config-sourced fields are included (heartbeat_interval, vcpus, inactive_heartbeat_count).
// Built-in/sourced fields (Version, Status, ControllerName, etc.) come from LoadBuiltinData
// and are not part of the config push conversion.
type rawClusterData struct {
	name                   string
	heartbeatInterval      int
	vcpus                  int
	inactiveHeartbeatCount int
}

// rawClusterToModel maps a rawClusterData to a models.ClusterInfo.
// Config-sourced fields only; built-in fields remain zero.
func rawClusterToModel(r rawClusterData) *models.ClusterInfo {
	return &models.ClusterInfo{
		ClusterName:            r.name,
		HeartbeatInterval:      r.heartbeatInterval,
		Vcpus:                  r.vcpus,
		InactiveHeartbeatCount: r.inactiveHeartbeatCount,
	}
}