//
// DISCLAIMER
//
// Copyright 2016-2023 ArangoDB GmbH, Cologne, Germany
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
//
// Copyright holder is ArangoDB GmbH, Cologne, Germany
//

package internal

import (
	_ "embed"
	"fmt"
	"html/template"
	"os"
	"path"
	"sort"

	"github.com/arangodb/kube-arangodb/internal/md"
	"github.com/arangodb/kube-arangodb/pkg/util/strings"
)

//go:embed metrics.go.tmpl
var metricsGoTemplate []byte

//go:embed metrics.item.go.tmpl
var metricsItemGoTemplate []byte

//go:embed metrics.item.tmpl
var metricItemTemplate []byte

//go:embed metrics.yaml
var metricsData []byte

type MetricsDoc struct {
	Destination   string `json:"destination" yaml:"destination"`
	Documentation string `json:"documentation" yaml:"documentation"`

	Namespaces Namespaces `json:"namespaces" yaml:"namespaces"`
}

type Namespaces map[string]Groups

func (n Namespaces) Keys() []string {
	r := make([]string, 0, len(n))

	for k := range n {
		r = append(r, k)
	}

	sort.Strings(r)

	return r
}

type Groups map[string]Metrics

func (n Groups) Keys() []string {
	r := make([]string, 0, len(n))

	for k := range n {
		r = append(r, k)
	}

	sort.Strings(r)

	return r
}

type Metrics map[string]Metric

func (n Metrics) Keys() []string {
	r := make([]string, 0, len(n))

	for k := range n {
		r = append(r, k)
	}

	sort.Strings(r)

	return r
}

type Metric struct {
	Description      string `json:"description" yaml:"description"`
	Type             string `json:"type" yaml:"type"`
	ShortDescription string `json:"shortDescription" yaml:"shortDescription"`

	Labels        []Label    `json:"labels" yaml:"labels"`
	AlertingRules []Alerting `json:"alertingRules" yaml:"alertingRules"`
}

type Alerting struct {
	Priority    string `json:"priority" yaml:"priority"`
	Query       string `json:"query" yaml:"query"`
	Description string `json:"description" yaml:"description"`
}

type Label struct {
	Key         string  `json:"key" yaml:"key"`
	Description string  `json:"description" yaml:"description"`
	Type        *string `json:"type" yaml:"type"`
}

func GenerateMetricsDocumentation(root string, in MetricsDoc) error {
	docsRoot := path.Join(root, in.Documentation)
	goFilesRoot := path.Join(root, in.Destination)

	if _, err := os.Stat(docsRoot); err != nil {
		if os.IsNotExist(err) {
			if err := os.MkdirAll(docsRoot, 0755); err != nil {
				return err
			}
		} else {
			return err
		}
	}

	if _, err := os.Stat(goFilesRoot); err != nil {
		if os.IsNotExist(err) {
			if err := os.MkdirAll(goFilesRoot, 0755); err != nil {
				return err
			}
		} else {
			return err
		}
	}

	if err := generateMetricsREADME(docsRoot, in); err != nil {
		return err
	}

	if err := generateMetricsGO(goFilesRoot, in); err != nil {
		return err
	}

	return nil
}

func generateMetricFile(root, name string, m Metric) error {
	key := md.NewColumn("Label", md.ColumnCenterAlign)
	description := md.NewColumn("Description", md.ColumnLeftAlign)
	priority := md.NewColumn("Priority", md.ColumnCenterAlign)
	query := md.NewColumn("Query", md.ColumnCenterAlign)
	t := md.NewTable(
		key,
		description,
	)

	for _, l := range m.Labels {
		if err := t.AddRow(map[md.Column]string{
			key:         l.Key,
			description: l.Description,
		}); err != nil {
			return err
		}
	}

	ta := md.NewTable(
		priority,
		query,
		description,
	)

	for _, l := range m.AlertingRules {
		if err := ta.AddRow(map[md.Column]string{
			priority:    l.Priority,
			query:       l.Query,
			description: l.Description,
		}); err != nil {
			return err
		}
	}

	q, err := template.New("metrics").Parse(string(metricItemTemplate))
	if err != nil {
		return err
	}

	out, err := os.OpenFile(path.Join(root, fmt.Sprintf("%s.md", name)), os.O_CREATE|os.O_TRUNC|os.O_WRONLY, 0644)
	if err != nil {
		return err
	}

	if err := q.Execute(out, map[string]interface{}{
		"name":           name,
		"type":           m.Type,
		"description":    m.Description,
		"labels_table":   t.Render(),
		"labels":         len(m.Labels) > 0,
		"alerting_table": ta.Render(),
		"alerting":       len(m.AlertingRules) > 0,
	}); err != nil {
		return err
	}

	if err := out.Close(); err != nil {
		return err
	}

	return nil
}

func generateMetricsREADME(root string, in MetricsDoc) error {
	name := md.NewColumn("Name", md.ColumnCenterAlign)
	ns := md.NewColumn("Namespace", md.ColumnCenterAlign)
	group := md.NewColumn("Group", md.ColumnCenterAlign)
	typeCol := md.NewColumn("Type", md.ColumnCenterAlign)
	description := md.NewColumn("Description", md.ColumnLeftAlign)
	t := md.NewTable(
		name,
		ns,
		group,
		typeCol,
		description,
	)

	for _, namespace := range in.Namespaces.Keys() {
		for _, g := range in.Namespaces[namespace].Keys() {
			for _, metric := range in.Namespaces[namespace][g].Keys() {
				mname := fmt.Sprintf("%s_%s_%s", namespace, g, metric)
				rname := fmt.Sprintf("[%s](./%s.md)", mname, mname)

				details := in.Namespaces[namespace][g][metric]

				if err := t.AddRow(map[md.Column]string{
					name:        rname,
					ns:          namespace,
					group:       g,
					description: details.ShortDescription,
					typeCol:     details.Type,
				}); err != nil {
					return err
				}

				if err := generateMetricFile(root, mname, details); err != nil {
					return err
				}
			}
		}
	}

	if err := md.ReplaceSectionsInFile(path.Join(root, "README.md"), map[string]string{
		"metricsTable": md.WrapWithNewLines(t.Render()),
	}); err != nil {
		return err
	}

	return nil
}

func generateLabels(labels []Label) string {
	if len(labels) == 0 {
		return "nil"
	}

	parts := make([]string, len(labels))

	for id := range labels {
		parts[id] = fmt.Sprintf("`%s`", labels[id].Key)
	}

	return fmt.Sprintf("[]string{%s}", strings.Join(parts, ", "))
}

func generateMetricsGO(root string, in MetricsDoc) error {
	i, err := template.New("metrics").Parse(string(metricsItemGoTemplate))

	if err != nil {
		return err
	}
	for _, namespace := range in.Namespaces.Keys() {
		for _, g := range in.Namespaces[namespace].Keys() {
			for _, metric := range in.Namespaces[namespace][g].Keys() {
				details := in.Namespaces[namespace][g][metric]

				mname := fmt.Sprintf("%s_%s_%s", namespace, g, metric)

				out, err := os.OpenFile(path.Join(root, fmt.Sprintf("%s.go", mname)), os.O_CREATE|os.O_TRUNC|os.O_WRONLY, 0644)
				if err != nil {
					return err
				}

				parts := strings.Split(mname, "_")
				tparts := strings.Split(strings.Title(strings.Join(parts, " ")), " ")

				fnameParts := make([]string, len(parts))
				for id := range parts {
					if id == 0 {
						fnameParts[id] = parts[id]
					} else {
						fnameParts[id] = tparts[id]
					}
				}

				var keys []string
				var params []string

				params = append(params, "value float64")
				keys = append(keys, "value")

				for _, label := range details.Labels {
					v := strings.Split(strings.ToLower(label.Key), "_")
					for id := range v {
						if id == 0 {
							continue
						}

						v[id] = strings.Title(v[id])
					}

					k := strings.Join(v, "")

					keys = append(keys, k)

					if t := label.Type; t != nil {
						params = append(params, fmt.Sprintf("%s %s", k, *t))
					} else {
						params = append(params, fmt.Sprintf("%s string", k))
					}
				}

				if err := i.Execute(out, map[string]interface{}{
					"name":             mname,
					"fname":            strings.Join(fnameParts, ""),
					"ename":            strings.Join(tparts, ""),
					"shortDescription": details.ShortDescription,
					"labels":           generateLabels(details.Labels),
					"type":             details.Type,
					"fparams":          strings.Join(params, ", "),
					"fkeys":            strings.Join(keys, ", "),
				}); err != nil {
					return err
				}

				if err := out.Close(); err != nil {
					return err
				}
			}
		}
	}

	out, err := os.OpenFile(path.Join(root, "metrics.go"), os.O_CREATE|os.O_TRUNC|os.O_WRONLY, 0644)
	if err != nil {
		return err
	}

	q, err := template.New("metrics").Parse(string(metricsGoTemplate))
	if err != nil {
		return err
	}

	if err := q.Execute(out, nil); err != nil {
		return err
	}

	if err := out.Close(); err != nil {
		return err
	}

	return nil
}