// Copyright (C) 2022 NHR@FAU, University Erlangen-Nuremberg.
// All rights reserved.
// Use of this source code is governed by a MIT-style
// license that can be found in the LICENSE file.
package metricdata

import (
	"bufio"
	"bytes"
	"context"
	"encoding/json"
	"fmt"
	"net/http"
	"strconv"
	"strings"
	"time"

	"github.com/ClusterCockpit/cc-backend/pkg/archive"
	"github.com/ClusterCockpit/cc-backend/pkg/schema"
)

type CCMetricStoreConfig struct {
	Kind  string `json:"kind"`
	Url   string `json:"url"`
	Token string `json:"token"`

	// If metrics are known to this MetricDataRepository under a different
	// name than in the `metricConfig` section of the 'cluster.json',
	// provide this optional mapping of local to remote name for this metric.
	Renamings map[string]string `json:"metricRenamings"`
}

type CCMetricStore struct {
	jwt           string
	url           string
	queryEndpoint string
	client        http.Client
	here2there    map[string]string
	there2here    map[string]string
}

type ApiQueryRequest struct {
	Cluster     string     `json:"cluster"`
	From        int64      `json:"from"`
	To          int64      `json:"to"`
	WithStats   bool       `json:"with-stats"`
	WithData    bool       `json:"with-data"`
	Queries     []ApiQuery `json:"queries"`
	ForAllNodes []string   `json:"for-all-nodes"`
}

type ApiQuery struct {
	Metric     string   `json:"metric"`
	Hostname   string   `json:"host"`
	Aggregate  bool     `json:"aggreg"`
	Type       *string  `json:"type,omitempty"`
	TypeIds    []string `json:"type-ids,omitempty"`
	SubType    *string  `json:"subtype,omitempty"`
	SubTypeIds []string `json:"subtype-ids,omitempty"`
}

type ApiQueryResponse struct {
	Queries []ApiQuery        `json:"queries,omitempty"`
	Results [][]ApiMetricData `json:"results"`
}

type ApiMetricData struct {
	Error *string        `json:"error"`
	From  int64          `json:"from"`
	To    int64          `json:"to"`
	Data  []schema.Float `json:"data"`
	Avg   schema.Float   `json:"avg"`
	Min   schema.Float   `json:"min"`
	Max   schema.Float   `json:"max"`
}

func (ccms *CCMetricStore) Init(rawConfig json.RawMessage) error {
	var config CCMetricStoreConfig
	if err := json.Unmarshal(rawConfig, &config); err != nil {
		return err
	}

	ccms.url = config.Url
	ccms.queryEndpoint = fmt.Sprintf("%s/api/query", config.Url)
	ccms.jwt = config.Token
	ccms.client = http.Client{
		Timeout: 10 * time.Second,
	}

	if config.Renamings != nil {
		ccms.here2there = config.Renamings
		ccms.there2here = make(map[string]string, len(config.Renamings))
		for k, v := range ccms.here2there {
			ccms.there2here[v] = k
		}
	} else {
		ccms.here2there = make(map[string]string)
		ccms.there2here = make(map[string]string)
	}

	return nil
}

func (ccms *CCMetricStore) toRemoteName(metric string) string {
	if renamed, ok := ccms.here2there[metric]; ok {
		return renamed
	}

	return metric
}

func (ccms *CCMetricStore) toLocalName(metric string) string {
	if renamed, ok := ccms.there2here[metric]; ok {
		return renamed
	}

	return metric
}

func (ccms *CCMetricStore) doRequest(ctx context.Context, body *ApiQueryRequest) (*ApiQueryResponse, error) {
	buf := &bytes.Buffer{}
	if err := json.NewEncoder(buf).Encode(body); err != nil {
		return nil, err
	}

	req, err := http.NewRequestWithContext(ctx, http.MethodPost, ccms.queryEndpoint, buf)
	if err != nil {
		return nil, err
	}
	if ccms.jwt != "" {
		req.Header.Add("Authorization", fmt.Sprintf("Bearer %s", ccms.jwt))
	}

	res, err := ccms.client.Do(req)
	if err != nil {
		return nil, err
	}

	if res.StatusCode != http.StatusOK {
		return nil, fmt.Errorf("'%s': HTTP Status: %s", ccms.queryEndpoint, res.Status)
	}

	var resBody ApiQueryResponse
	if err := json.NewDecoder(bufio.NewReader(res.Body)).Decode(&resBody); err != nil {
		return nil, err
	}

	return &resBody, nil
}

func (ccms *CCMetricStore) LoadData(job *schema.Job, metrics []string, scopes []schema.MetricScope, ctx context.Context) (schema.JobData, error) {
	topology := archive.GetSubCluster(job.Cluster, job.SubCluster).Topology
	queries, assignedScope, err := ccms.buildQueries(job, metrics, scopes)
	if err != nil {
		return nil, err
	}

	req := ApiQueryRequest{
		Cluster:   job.Cluster,
		From:      job.StartTime.Unix(),
		To:        job.StartTime.Add(time.Duration(job.Duration) * time.Second).Unix(),
		Queries:   queries,
		WithStats: true,
		WithData:  true,
	}

	resBody, err := ccms.doRequest(ctx, &req)
	if err != nil {
		return nil, err
	}

	var errors []string
	var jobData schema.JobData = make(schema.JobData)
	for i, row := range resBody.Results {
		query := req.Queries[i]
		metric := ccms.toLocalName(query.Metric)
		scope := assignedScope[i]
		mc := archive.GetMetricConfig(job.Cluster, metric)
		if _, ok := jobData[metric]; !ok {
			jobData[metric] = make(map[schema.MetricScope]*schema.JobMetric)
		}

		jobMetric, ok := jobData[metric][scope]
		if !ok {
			jobMetric = &schema.JobMetric{
				Unit:     mc.Unit,
				Scope:    scope,
				Timestep: mc.Timestep,
				Series:   make([]schema.Series, 0),
			}
			jobData[metric][scope] = jobMetric
		}

		for _, res := range row {
			if res.Error != nil {
				errors = append(errors, fmt.Sprintf("failed to fetch '%s' from host '%s': %s", query.Metric, query.Hostname, *res.Error))
				continue
			}

			id := (*int)(nil)
			if query.Type != nil {
				id = new(int)
				*id, err = strconv.Atoi(query.TypeIds[0])
				if err != nil || *query.Type == acceleratorString {
					*id, _ = topology.GetAcceleratorIndex(query.TypeIds[0])
				}
			}

			if res.Avg.IsNaN() || res.Min.IsNaN() || res.Max.IsNaN() {
				// TODO: use schema.Float instead of float64?
				// This is done because regular float64 can not be JSONed when NaN.
				res.Avg = schema.Float(0)
				res.Min = schema.Float(0)
				res.Max = schema.Float(0)
			}

			jobMetric.Series = append(jobMetric.Series, schema.Series{
				Hostname: query.Hostname,
				Id:       id,
				Statistics: &schema.MetricStatistics{
					Avg: float64(res.Avg),
					Min: float64(res.Min),
					Max: float64(res.Max),
				},
				Data: res.Data,
			})
		}

		// So that one can later check len(jobData):
		if len(jobMetric.Series) == 0 {
			delete(jobData[metric], scope)
			if len(jobData[metric]) == 0 {
				delete(jobData, metric)
			}
		}
	}

	if len(errors) != 0 {
		return jobData, fmt.Errorf("cc-metric-store: %s", strings.Join(errors, ", "))
	}

	return jobData, nil
}

var (
	hwthreadString     = string(schema.MetricScopeHWThread)
	coreString         = string(schema.MetricScopeCore)
	memoryDomainString = string(schema.MetricScopeMemoryDomain)
	socketString       = string(schema.MetricScopeSocket)
	acceleratorString  = string(schema.MetricScopeAccelerator)
)

func (ccms *CCMetricStore) buildQueries(job *schema.Job, metrics []string, scopes []schema.MetricScope) ([]ApiQuery, []schema.MetricScope, error) {
	queries := make([]ApiQuery, 0, len(metrics)*len(scopes)*len(job.Resources))
	topology := archive.GetSubCluster(job.Cluster, job.SubCluster).Topology
	assignedScope := []schema.MetricScope{}

	for _, metric := range metrics {
		remoteName := ccms.toRemoteName(metric)
		mc := archive.GetMetricConfig(job.Cluster, metric)
		if mc == nil {
			// return nil, fmt.Errorf("metric '%s' is not specified for cluster '%s'", metric, job.Cluster)
			// log.Printf("metric '%s' is not specified for cluster '%s'", metric, job.Cluster)
			continue
		}

		// Avoid duplicates...
		handledScopes := make([]schema.MetricScope, 0, 3)

	scopesLoop:
		for _, requestedScope := range scopes {
			nativeScope := mc.Scope
			if nativeScope == schema.MetricScopeAccelerator && job.NumAcc == 0 {
				continue
			}

			scope := nativeScope.Max(requestedScope)
			for _, s := range handledScopes {
				if scope == s {
					continue scopesLoop
				}
			}
			handledScopes = append(handledScopes, scope)

			for _, host := range job.Resources {
				hwthreads := host.HWThreads
				if hwthreads == nil {
					hwthreads = topology.Node
				}

				// Accelerator -> Accelerator (Use "accelerator" scope if requested scope is lower than node)
				if nativeScope == schema.MetricScopeAccelerator && scope.LT(schema.MetricScopeNode) {
					queries = append(queries, ApiQuery{
						Metric:    remoteName,
						Hostname:  host.Hostname,
						Aggregate: false,
						Type:      &acceleratorString,
						TypeIds:   host.Accelerators,
					})
					assignedScope = append(assignedScope, schema.MetricScopeAccelerator)
					continue
				}

				// Accelerator -> Node
				if nativeScope == schema.MetricScopeAccelerator && scope == schema.MetricScopeNode {
					if len(host.Accelerators) == 0 {
						continue
					}

					queries = append(queries, ApiQuery{
						Metric:    remoteName,
						Hostname:  host.Hostname,
						Aggregate: true,
						Type:      &acceleratorString,
						TypeIds:   host.Accelerators,
					})
					assignedScope = append(assignedScope, scope)
					continue
				}

				// HWThread -> HWThead
				if nativeScope == schema.MetricScopeHWThread && scope == schema.MetricScopeHWThread {
					queries = append(queries, ApiQuery{
						Metric:    remoteName,
						Hostname:  host.Hostname,
						Aggregate: false,
						Type:      &hwthreadString,
						TypeIds:   intToStringSlice(hwthreads),
					})
					assignedScope = append(assignedScope, scope)
					continue
				}

				// HWThread -> Core
				if nativeScope == schema.MetricScopeHWThread && scope == schema.MetricScopeCore {
					cores, _ := topology.GetCoresFromHWThreads(hwthreads)
					for _, core := range cores {
						queries = append(queries, ApiQuery{
							Metric:    remoteName,
							Hostname:  host.Hostname,
							Aggregate: true,
							Type:      &hwthreadString,
							TypeIds:   intToStringSlice(topology.Core[core]),
						})
						assignedScope = append(assignedScope, scope)
					}
					continue
				}

				// HWThread -> Socket
				if nativeScope == schema.MetricScopeHWThread && scope == schema.MetricScopeSocket {
					sockets, _ := topology.GetSocketsFromHWThreads(hwthreads)
					for _, socket := range sockets {
						queries = append(queries, ApiQuery{
							Metric:    remoteName,
							Hostname:  host.Hostname,
							Aggregate: true,
							Type:      &hwthreadString,
							TypeIds:   intToStringSlice(topology.Socket[socket]),
						})
						assignedScope = append(assignedScope, scope)
					}
					continue
				}

				// HWThread -> Node
				if nativeScope == schema.MetricScopeHWThread && scope == schema.MetricScopeNode {
					queries = append(queries, ApiQuery{
						Metric:    remoteName,
						Hostname:  host.Hostname,
						Aggregate: true,
						Type:      &hwthreadString,
						TypeIds:   intToStringSlice(hwthreads),
					})
					assignedScope = append(assignedScope, scope)
					continue
				}

				// Core -> Core
				if nativeScope == schema.MetricScopeCore && scope == schema.MetricScopeCore {
					cores, _ := topology.GetCoresFromHWThreads(hwthreads)
					queries = append(queries, ApiQuery{
						Metric:    remoteName,
						Hostname:  host.Hostname,
						Aggregate: false,
						Type:      &coreString,
						TypeIds:   intToStringSlice(cores),
					})
					assignedScope = append(assignedScope, scope)
					continue
				}

				// Core -> Node
				if nativeScope == schema.MetricScopeCore && scope == schema.MetricScopeNode {
					cores, _ := topology.GetCoresFromHWThreads(hwthreads)
					queries = append(queries, ApiQuery{
						Metric:    remoteName,
						Hostname:  host.Hostname,
						Aggregate: true,
						Type:      &coreString,
						TypeIds:   intToStringSlice(cores),
					})
					assignedScope = append(assignedScope, scope)
					continue
				}

				// MemoryDomain -> MemoryDomain
				if nativeScope == schema.MetricScopeMemoryDomain && scope == schema.MetricScopeMemoryDomain {
					sockets, _ := topology.GetMemoryDomainsFromHWThreads(hwthreads)
					queries = append(queries, ApiQuery{
						Metric:    remoteName,
						Hostname:  host.Hostname,
						Aggregate: false,
						Type:      &memoryDomainString,
						TypeIds:   intToStringSlice(sockets),
					})
					assignedScope = append(assignedScope, scope)
					continue
				}

				// MemoryDoman -> Node
				if nativeScope == schema.MetricScopeMemoryDomain && scope == schema.MetricScopeNode {
					sockets, _ := topology.GetMemoryDomainsFromHWThreads(hwthreads)
					queries = append(queries, ApiQuery{
						Metric:    remoteName,
						Hostname:  host.Hostname,
						Aggregate: true,
						Type:      &memoryDomainString,
						TypeIds:   intToStringSlice(sockets),
					})
					assignedScope = append(assignedScope, scope)
					continue
				}

				// Socket -> Socket
				if nativeScope == schema.MetricScopeSocket && scope == schema.MetricScopeSocket {
					sockets, _ := topology.GetSocketsFromHWThreads(hwthreads)
					queries = append(queries, ApiQuery{
						Metric:    remoteName,
						Hostname:  host.Hostname,
						Aggregate: false,
						Type:      &socketString,
						TypeIds:   intToStringSlice(sockets),
					})
					assignedScope = append(assignedScope, scope)
					continue
				}

				// Socket -> Node
				if nativeScope == schema.MetricScopeSocket && scope == schema.MetricScopeNode {
					sockets, _ := topology.GetSocketsFromHWThreads(hwthreads)
					queries = append(queries, ApiQuery{
						Metric:    remoteName,
						Hostname:  host.Hostname,
						Aggregate: true,
						Type:      &socketString,
						TypeIds:   intToStringSlice(sockets),
					})
					assignedScope = append(assignedScope, scope)
					continue
				}

				// Node -> Node
				if nativeScope == schema.MetricScopeNode && scope == schema.MetricScopeNode {
					queries = append(queries, ApiQuery{
						Metric:   remoteName,
						Hostname: host.Hostname,
					})
					assignedScope = append(assignedScope, scope)
					continue
				}

				return nil, nil, fmt.Errorf("TODO: unhandled case: native-scope=%s, requested-scope=%s", nativeScope, requestedScope)
			}
		}
	}

	return queries, assignedScope, nil
}

func (ccms *CCMetricStore) LoadStats(job *schema.Job, metrics []string, ctx context.Context) (map[string]map[string]schema.MetricStatistics, error) {
	queries, _, err := ccms.buildQueries(job, metrics, []schema.MetricScope{schema.MetricScopeNode})
	if err != nil {
		return nil, err
	}

	req := ApiQueryRequest{
		Cluster:   job.Cluster,
		From:      job.StartTime.Unix(),
		To:        job.StartTime.Add(time.Duration(job.Duration) * time.Second).Unix(),
		Queries:   queries,
		WithStats: true,
		WithData:  false,
	}

	resBody, err := ccms.doRequest(ctx, &req)
	if err != nil {
		return nil, err
	}

	stats := make(map[string]map[string]schema.MetricStatistics, len(metrics))
	for i, res := range resBody.Results {
		query := req.Queries[i]
		metric := ccms.toLocalName(query.Metric)
		data := res[0]
		if data.Error != nil {
			return nil, fmt.Errorf("fetching %s for node %s failed: %s", metric, query.Hostname, *data.Error)
		}

		metricdata, ok := stats[metric]
		if !ok {
			metricdata = make(map[string]schema.MetricStatistics, job.NumNodes)
			stats[metric] = metricdata
		}

		if data.Avg.IsNaN() || data.Min.IsNaN() || data.Max.IsNaN() {
			return nil, fmt.Errorf("fetching %s for node %s failed: %s", metric, query.Hostname, "avg/min/max is NaN")
		}

		metricdata[query.Hostname] = schema.MetricStatistics{
			Avg: float64(data.Avg),
			Min: float64(data.Min),
			Max: float64(data.Max),
		}
	}

	return stats, nil
}

// TODO: Support sub-node-scope metrics! For this, the partition of a node needs to be known!
func (ccms *CCMetricStore) LoadNodeData(cluster string, metrics, nodes []string, scopes []schema.MetricScope, from, to time.Time, ctx context.Context) (map[string]map[string][]*schema.JobMetric, error) {
	req := ApiQueryRequest{
		Cluster:   cluster,
		From:      from.Unix(),
		To:        to.Unix(),
		WithStats: true,
		WithData:  true,
	}

	if nodes == nil {
		for _, metric := range metrics {
			req.ForAllNodes = append(req.ForAllNodes, ccms.toRemoteName(metric))
		}
	} else {
		for _, node := range nodes {
			for _, metric := range metrics {
				req.Queries = append(req.Queries, ApiQuery{
					Hostname: node,
					Metric:   ccms.toRemoteName(metric),
				})
			}
		}
	}

	resBody, err := ccms.doRequest(ctx, &req)
	if err != nil {
		return nil, err
	}

	var errors []string
	data := make(map[string]map[string][]*schema.JobMetric)
	for i, res := range resBody.Results {
		var query ApiQuery
		if resBody.Queries != nil {
			query = resBody.Queries[i]
		} else {
			query = req.Queries[i]
		}

		metric := ccms.toLocalName(query.Metric)
		qdata := res[0]
		if qdata.Error != nil {
			errors = append(errors, fmt.Sprintf("fetching %s for node %s failed: %s", metric, query.Hostname, *qdata.Error))
		}

		if qdata.Avg.IsNaN() || qdata.Min.IsNaN() || qdata.Max.IsNaN() {
			// return nil, fmt.Errorf("fetching %s for node %s failed: %s", metric, query.Hostname, "avg/min/max is NaN")
			qdata.Avg, qdata.Min, qdata.Max = 0., 0., 0.
		}

		hostdata, ok := data[query.Hostname]
		if !ok {
			hostdata = make(map[string][]*schema.JobMetric)
			data[query.Hostname] = hostdata
		}

		mc := archive.GetMetricConfig(cluster, metric)
		hostdata[metric] = append(hostdata[metric], &schema.JobMetric{
			Unit:     mc.Unit,
			Scope:    schema.MetricScopeNode,
			Timestep: mc.Timestep,
			Series: []schema.Series{
				{
					Hostname: query.Hostname,
					Data:     qdata.Data,
					Statistics: &schema.MetricStatistics{
						Avg: float64(qdata.Avg),
						Min: float64(qdata.Min),
						Max: float64(qdata.Max),
					},
				},
			},
		})
	}

	if len(errors) != 0 {
		return data, fmt.Errorf("cc-metric-store: %s", strings.Join(errors, ", "))
	}

	return data, nil
}

func intToStringSlice(is []int) []string {
	ss := make([]string, len(is))
	for i, x := range is {
		ss[i] = strconv.Itoa(x)
	}
	return ss
}