package compose

import (
	"encoding/json"
	"errors"
	"fmt"
	"slices"
	"sort"
	"strings"

	"git.novox.be/novox/mesh-sdk/go/declaration"
	"git.novox.be/novox/mesh-sdk/go/delivery"
)

// Compositions is one node's compositions (novox/hq ADR 0539 clauses 1 and 2): its declaration composed over in, as
// the controller composes it, split into each module's composition at the fingerprint fps gives it and the node's own
// (`<node>.node`), by key (delivery.ComposedKey). Each resource says its module, whatever the node reported it reads.
// A module fps gives no fingerprint for is not composed and is named in skipped, so a caller composing one module
// (mesh-hand-compose) gets that one. Each module's Data says whether its manifest declares data. The compositions are not
// signed and not yet by digest: the writer does both (delivery.SignComposed, Composed.ByDigest).
func Compositions(in Input, node string, fps map[string]string, mode Mode) (out map[string]delivery.Composed, skipped []string, err error) {
	out, skipped, _, err = compositions(in, node, fps, mode, false)
	return out, skipped, err
}

// ErrStoodIn is a composition that holds a stand-in for a value the input does not carry (an own secret, a grant's
// sealed copy, a vault box, the certificate, the bus's user list) or a port it does not give: what a send would make,
// never what may be applied.
var ErrStoodIn = errors.New("compose: the composition stands in for what its input does not carry")

// BusUsersStandIn is what a composition says it stood in for when its input carries no bus user list.
const BusUsersStandIn = "the bus's user list"

// CompositionsApplied is Compositions for a node that applies what it composed itself (novox/hq ADR 0547 §2, issue
// 1126): a declaration that stands in for anything (Declared.StoodIn, Foreseen, ForeseenPorts) is refused with
// ErrStoodIn, naming each, so a stand-in is never applied as if it were the value; but for the bus's user list
// (BusUsersStandIn), which the bus node holds out of every apply of a composition it made itself.
func CompositionsApplied(in Input, node string, fps map[string]string) (map[string]delivery.Composed, []string, error) {
	out, skipped, _, err := compositions(in, node, fps, Reading, true)
	return out, skipped, err
}

// CompositionsShadow is CompositionsApplied for a composition that is compared and never applied (a node's answer to a
// placement candidate, novox/hq ADR 0559 §4): composed in the Foreseeing mode, so an own secret never issued (a module
// the candidate adds) is a named stand-in rather than an error, and what it stands in for is answered (stood, sorted,
// the bus's user list left out) rather than refused, so the caller judges each stand-in: a value not yet issued for a
// module the candidate adds, or one missing for a module the node runs. A module whose every value is held composes
// as CompositionsApplied composes it: the modes differ only in an own secret never issued.
func CompositionsShadow(in Input, node string, fps map[string]string) (out map[string]delivery.Composed, skipped, stood []string, err error) {
	return compositions(in, node, fps, Foreseeing, false)
}

func compositions(in Input, node string, fps map[string]string, mode Mode, applied bool) (out map[string]delivery.Composed, skipped, stood []string, err error) {
	reading := in
	reading.Nodes = append([]Node(nil), in.Nodes...)
	found := false
	for i := range reading.Nodes {
		if reading.Nodes[i].Name == node {
			reading.Nodes[i].ReadsModules = true
			found = true
		}
	}
	if !found {
		return nil, nil, nil, fmt.Errorf("compose: the mesh has no node %q", node)
	}
	d, problems, err := ComposeIn(reading, node, mode)
	if err != nil {
		return nil, nil, nil, err
	}
	if len(problems) > 0 {
		return nil, nil, nil, fmt.Errorf("compose: %s's declaration is refused by the node-engine's validator: %v", node, problems)
	}
	for _, x := range d.StoodIn {
		// The bus's user list is the bus node's own to follow, written alone and never from a composition the node
		// made itself (ADR 0547 §7, §8): its stand-in is held out of the apply, not applied.
		if x != BusUsersStandIn {
			stood = append(stood, x)
		}
	}
	stood = append(stood, d.Foreseen...)
	for _, p := range d.ForeseenPorts {
		stood = append(stood, "port "+p)
	}
	sort.Strings(stood)
	stood = slices.Compact(stood) // an own secret is both stood in for and foreseen
	if applied && len(stood) > 0 {
		return nil, nil, nil, fmt.Errorf("%w on %s: %s", ErrStoodIn, node, strings.Join(stood, ", "))
	}
	body, err := d.Body()
	if err != nil {
		return nil, nil, nil, err
	}
	var envelope struct {
		Resources   []json.RawMessage     `json:"resources"`
		Adoption    *declaration.Adoption `json:"adoption"`
		Filled      []string              `json:"filled_files"`
		Provisioner string                `json:"provisioner_account"`
	}
	if err := json.Unmarshal(body, &envelope); err != nil {
		return nil, nil, nil, err
	}
	var kept []json.RawMessage
	keptPaths := map[string]bool{}
	left := map[string]bool{}
	for _, raw := range envelope.Resources {
		var head struct {
			Module string `json:"module"`
			Type   string `json:"type"`
			Path   string `json:"path"`
		}
		if err := json.Unmarshal(raw, &head); err != nil {
			return nil, nil, nil, err
		}
		if _, ok := fps[head.Module]; head.Module != "" && !ok {
			left[head.Module] = true
			continue
		}
		if head.Type == string(declaration.TypeFile) {
			keptPaths[head.Path] = true
		}
		kept = append(kept, raw)
	}
	var filled []string
	for _, p := range envelope.Filled {
		if keptPaths[p] {
			filled = append(filled, p)
		}
	}
	out, err = delivery.SplitComposed(node, kept, fps, filled,
		delivery.NodeOwn{Adoption: envelope.Adoption, Provisioner: envelope.Provisioner})
	if err != nil {
		return nil, nil, nil, err
	}
	for key, c := range out {
		if m, ok := in.Catalogue[c.Module]; ok && c.Module != "" {
			c.Data = len(m.DataItems()) > 0
			out[key] = c
		}
	}
	for m := range left {
		skipped = append(skipped, m)
	}
	sort.Strings(skipped)
	return out, skipped, stood, nil
}