package main

import (
	"encoding/json"
	"fmt"
	"io"
	"os"
	"strconv"
	"strings"

	"github.com/spf13/cobra"
	"go.yaml.in/yaml/v3"

	"jarl/internal/api"
	"jarl/internal/client"
)

// batchFile is the format of 'jarl apply -f'.
type batchFile struct {
	Description string       `yaml:"description" json:"description"`
	Changes     []batchEntry `yaml:"changes" json:"changes"`
}

type batchEntry struct {
	Add    map[string]any `yaml:"add,omitempty" json:"add,omitempty"`
	Delete map[string]any `yaml:"delete,omitempty" json:"delete,omitempty"`
	Set    map[string]any `yaml:"set,omitempty" json:"set,omitempty"`
	Update map[string]any `yaml:"update,omitempty" json:"update,omitempty"`
	// Any API operation: op, id, data.
	Op   string         `yaml:"op,omitempty" json:"op,omitempty"`
	ID   int64          `yaml:"id,omitempty" json:"id,omitempty"`
	Data map[string]any `yaml:"data,omitempty" json:"data,omitempty"`
}

func toInt64(v any) (int64, bool) {
	switch n := v.(type) {
	case int:
		return int64(n), true
	case int64:
		return n, true
	case float64:
		return int64(n), true
	case string:
		i, err := strconv.ParseInt(n, 10, 64)
		return i, err == nil
	}
	return 0, false
}

func rawJSON(v any) json.RawMessage {
	b, _ := json.Marshal(v)
	return b
}

// requests converts the file's entries into API change requests.
func (b *batchFile) requests() ([]api.ChangeRequest, error) {
	var out []api.ChangeRequest
	for i, e := range b.Changes {
		n := 0
		for _, set := range []bool{e.Add != nil, e.Delete != nil, e.Set != nil, e.Update != nil, e.Op != ""} {
			if set {
				n++
			}
		}
		if n != 1 {
			return nil, fmt.Errorf("change %d: use exactly one of add, delete, set, update or op", i+1)
		}
		switch {
		case e.Add != nil:
			out = append(out, api.ChangeRequest{Op: "record.create", Data: rawJSON(e.Add)})
		case e.Delete != nil:
			d := e.Delete
			if id, ok := toInt64(d["id"]); ok {
				delete(d, "id")
				out = append(out, api.ChangeRequest{Op: "record.delete", ID: id, Data: rawJSON(d)})
			} else {
				out = append(out, api.ChangeRequest{Op: "record.delete", Data: rawJSON(d)})
			}
		case e.Set != nil:
			s := e.Set
			switch d := s["data"].(type) {
			case string:
				s["data"] = []string{d}
			case nil:
				s["data"] = []string{}
			}
			out = append(out, api.ChangeRequest{Op: "rrset.replace", Data: rawJSON(s)})
		case e.Update != nil:
			u := e.Update
			id, ok := toInt64(u["id"])
			if !ok {
				return nil, fmt.Errorf("change %d: update needs the record id", i+1)
			}
			delete(u, "id")
			out = append(out, api.ChangeRequest{Op: "record.update", ID: id, Data: rawJSON(u)})
		default:
			var data json.RawMessage
			if e.Data != nil {
				data = rawJSON(e.Data)
			}
			out = append(out, api.ChangeRequest{Op: e.Op, ID: e.ID, Data: data})
		}
	}
	return out, nil
}

// submitBatch applies requests as one changeset, or stages them into the
// changeset given with --changeset.
func submitBatch(c *client.Client, description string, reqs []api.ChangeRequest) error {
	var resp api.MutationResponse
	if c.Changeset > 0 {
		if err := c.Do(ctx(), "POST", fmt.Sprintf("/changesets/%d/ops", c.Changeset), nil, map[string]any{"ops": reqs}, &resp); err != nil {
			return err
		}
		return report(&resp)
	}
	if err := c.Do(ctx(), "POST", "/apply", nil, api.BatchRequest{Description: description, Ops: reqs, DryRun: c.DryRun, Force: c.Force}, &resp); err != nil {
		return err
	}
	return report(&resp)
}

func applyCmd() *cobra.Command {
	var file, desc string
	cmd := &cobra.Command{
		Use:   "apply -f FILE",
		Short: "Apply a batch of changes from a YAML or JSON file, all or nothing",
		Long: `Applies the changes in FILE ('-' for standard input) as one changeset: they
are validated together and either all are applied or none.

  description: move the web server
  changes:
    - add:    {zone: example.com, name: www2, type: A, data: 192.0.2.20, ttl: 300, ptr: true}
    - delete: {zone: example.com, name: www, type: A}                 # every A record of www
    - delete: {zone: example.com, name: old, type: CNAME, data: www}  # just this record
    - delete: {id: 1234}
    - set:    {zone: example.com, name: api, type: A, data: [192.0.2.30, 192.0.2.31], ttl: 60}
    - update: {id: 1235, data: 192.0.2.40}
    - op: zone.create                                                  # any API operation
      data: {name: lab.example.com, nameservers: [ns1.example.com.]}

Records name zones by name (add "view: NAME" when the zone exists in several
views). With --changeset the changes are staged instead; with --dry-run they
are only validated.`,
		RunE: func(cmd *cobra.Command, args []string) error {
			if file == "" {
				return fmt.Errorf("-f FILE is required")
			}
			var data []byte
			var err error
			if file == "-" {
				data, err = io.ReadAll(os.Stdin)
			} else {
				data, err = os.ReadFile(file)
			}
			if err != nil {
				return err
			}
			var b batchFile
			if err := yaml.Unmarshal(data, &b); err != nil {
				return fmt.Errorf("%s: %w", file, err)
			}
			if desc != "" {
				b.Description = desc
			}
			reqs, err := b.requests()
			if err != nil {
				return err
			}
			if len(reqs) == 0 {
				return fmt.Errorf("%s has no changes", file)
			}
			c, err := newClient()
			if err != nil {
				return err
			}
			return submitBatch(c, b.Description, reqs)
		},
	}
	cmd.Flags().StringVarP(&file, "file", "f", "", "file with the changes ('-' for standard input)")
	cmd.Flags().StringVar(&desc, "description", "", "description for the history")
	return cmd
}

func changesetCmd() *cobra.Command {
	cmd := &cobra.Command{Use: "changeset", Aliases: []string{"cs"}, Short: "Stage changes and apply them together"}
	var status string
	var mine bool
	list := &cobra.Command{
		Use:   "list",
		Short: "List changesets (open ones by default)",
		RunE: func(cmd *cobra.Command, args []string) error {
			c, err := newClient()
			if err != nil {
				return err
			}
			qv := q("status", status)
			if mine {
				qv.Set("mine", "1")
			}
			var list []api.Changeset
			if err := c.Get(ctx(), "/changesets", qv, &list); err != nil {
				return err
			}
			return output(list, func(w io.Writer) {
				fmt.Fprintln(w, "ID\tSTATUS\tUSER\tVIA\tOPS\tDESCRIPTION")
				for _, cs := range list {
					fmt.Fprintf(w, "%d\t%s\t%s\t%s\t%d\t%s\n", cs.ID, cs.Status, cs.Username, cs.Via, len(cs.Ops), cs.Description)
				}
			})
		},
	}
	list.Flags().StringVar(&status, "status", "open", "open, applied or discarded (empty for all)")
	list.Flags().BoolVar(&mine, "mine", false, "only my changesets")
	create := &cobra.Command{
		Use:   "create [DESCRIPTION]",
		Short: "Start a changeset; prints its ID",
		Example: `  export JARL_CHANGESET=$(jarl changeset create "move web servers" -q)
  jarl record add example.com www2 A 192.0.2.20
  jarl record delete example.com www A
  jarl changeset diff $JARL_CHANGESET
  jarl changeset apply $JARL_CHANGESET`,
		RunE: func(cmd *cobra.Command, args []string) error {
			c, err := newClient()
			if err != nil {
				return err
			}
			var cs api.Changeset
			if err := c.Do(ctx(), "POST", "/changesets", nil, map[string]any{"description": strings.Join(args, " ")}, &cs); err != nil {
				return err
			}
			if flagQuiet {
				fmt.Println(cs.ID)
				return nil
			}
			fmt.Printf("created changeset %d\nstage changes with --changeset %d (or export JARL_CHANGESET=%d)\n", cs.ID, cs.ID, cs.ID)
			return nil
		},
	}
	show := &cobra.Command{
		Use:   "show ID",
		Short: "Show a changeset's operations",
		Args:  cobra.ExactArgs(1),
		RunE: func(cmd *cobra.Command, args []string) error {
			c, err := newClient()
			if err != nil {
				return err
			}
			var cs api.Changeset
			if err := c.Get(ctx(), "/changesets/"+args[0], nil, &cs); err != nil {
				return err
			}
			return output(cs, func(w io.Writer) {
				fmt.Fprintf(w, "Changeset:\t%d (%s)\nDescription:\t%s\nCreated:\t%s by %s via %s\n", cs.ID, cs.Status, cs.Description, cs.CreatedAt.Format("2006-01-02 15:04"), cs.Username, cs.Via)
				if cs.AppliedAt != nil {
					fmt.Fprintf(w, "Applied:\t%s by %s\n", cs.AppliedAt.Format("2006-01-02 15:04"), cs.AppliedBy)
				}
				fmt.Fprintln(w, "\n#\tOPERATION")
				for _, op := range cs.Ops {
					fmt.Fprintf(w, "%d\t%s\n", op.Seq, op.Summary)
				}
				if cs.Diff != "" {
					w.(interface{ Flush() error }).Flush()
					fmt.Println()
					fmt.Print(cs.Diff)
				}
			})
		},
	}
	diff := &cobra.Command{
		Use:   "diff ID",
		Short: "Validate an open changeset and show what applying it would change",
		Args:  cobra.ExactArgs(1),
		RunE: func(cmd *cobra.Command, args []string) error {
			c, err := newClient()
			if err != nil {
				return err
			}
			var raw json.RawMessage
			if err := c.Get(ctx(), "/changesets/"+args[0]+"/preview", nil, &raw); err != nil {
				return err
			}
			if flagOutput != "table" {
				var v any
				json.Unmarshal(raw, &v)
				return output(v, nil)
			}
			r := client.ParseResult(raw)
			for _, op := range r.Ops {
				fmt.Printf("#%d %s\n", op.Seq, op.Summary)
			}
			if r.Error != nil {
				fmt.Println("error:", r.Error.Message)
			}
			printProblems(os.Stdout, r.Problems)
			printCheck(os.Stdout, r.Check)
			for _, w := range r.Warnings {
				fmt.Println("warning:", w)
			}
			fmt.Println()
			fmt.Print(r.Diff)
			if r.Valid {
				fmt.Println("\nvalid: apply with 'jarl changeset apply " + args[0] + "'")
				return nil
			}
			return fmt.Errorf("the changeset can't be applied as it is")
		},
	}
	apply := &cobra.Command{
		Use:   "apply ID",
		Short: "Apply an open changeset",
		Args:  cobra.ExactArgs(1),
		RunE: func(cmd *cobra.Command, args []string) error {
			c, err := newClient()
			if err != nil {
				return err
			}
			var resp api.MutationResponse
			if err := c.Do(ctx(), "POST", "/changesets/"+args[0]+"/apply", nil, map[string]any{"force": c.Force, "dry_run": c.DryRun}, &resp); err != nil {
				return err
			}
			return report(&resp)
		},
	}
	discard := &cobra.Command{
		Use:   "discard ID",
		Short: "Throw away an open changeset",
		Args:  cobra.ExactArgs(1),
		RunE: func(cmd *cobra.Command, args []string) error {
			c, err := newClient()
			if err != nil {
				return err
			}
			if err := c.Do(ctx(), "POST", "/changesets/"+args[0]+"/discard", nil, nil, nil); err != nil {
				return err
			}
			if !flagQuiet {
				fmt.Println("discarded changeset", args[0])
			}
			return nil
		},
	}
	remove := &cobra.Command{
		Use:   "remove ID SEQ",
		Short: "Remove one operation from an open changeset",
		Args:  cobra.ExactArgs(2),
		RunE: func(cmd *cobra.Command, args []string) error {
			c, err := newClient()
			if err != nil {
				return err
			}
			return c.Do(ctx(), "DELETE", "/changesets/"+args[0]+"/ops/"+args[1], nil, nil, nil)
		},
	}
	revert := &cobra.Command{
		Use:   "revert ID",
		Short: "Create a changeset that undoes an applied changeset (review it, then apply)",
		Args:  cobra.ExactArgs(1),
		RunE: func(cmd *cobra.Command, args []string) error {
			c, err := newClient()
			if err != nil {
				return err
			}
			var cs api.Changeset
			if err := c.Do(ctx(), "POST", "/changesets/"+args[0]+"/revert", nil, nil, &cs); err != nil {
				return err
			}
			if flagQuiet {
				fmt.Println(cs.ID)
				return nil
			}
			fmt.Printf("created changeset %d with %d operations; review with 'jarl changeset diff %d', apply with 'jarl changeset apply %d'\n", cs.ID, len(cs.Ops), cs.ID, cs.ID)
			return nil
		},
	}
	cmd.AddCommand(list, create, show, diff, apply, discard, remove, revert)
	return cmd
}

func historyCmd() *cobra.Command {
	var limit int
	cmd := &cobra.Command{
		Use:   "history",
		Short: "List applied changesets",
		RunE: func(cmd *cobra.Command, args []string) error {
			c, err := newClient()
			if err != nil {
				return err
			}
			var list []api.Changeset
			if err := c.Get(ctx(), "/changesets", q("status", "applied", "limit", fmt.Sprint(limit)), &list); err != nil {
				return err
			}
			return output(list, func(w io.Writer) {
				fmt.Fprintln(w, "ID\tAPPLIED\tBY\tVIA\tOPS\tDESCRIPTION")
				for _, cs := range list {
					at := ""
					if cs.AppliedAt != nil {
						at = cs.AppliedAt.Local().Format("2006-01-02 15:04")
					}
					fmt.Fprintf(w, "%d\t%s\t%s\t%s\t%d\t%s\n", cs.ID, at, cs.AppliedBy, cs.Via, len(cs.Ops), cs.Description)
				}
			})
		},
	}
	cmd.Flags().IntVar(&limit, "limit", 30, "how many")
	return cmd
}