package catalogue

import (
	"fmt"
	"regexp"
	"sort"
	"strings"
)

// A directory the mesh places (novox/hq ADR 0112, to-be 27, issue 119).
//
// **A module definition names no host path.** A directory resource may omit `path`; the mesh
// resolves where it lands when the declaration is composed — `<root>/<module>/<id>`, the root a
// node's own setting with /var/lib as the default. From then on the module's own files, mounts
// and environment name the place as `${dir:<id>}`, the same shape as `${bound:…}` and
// `${secret:…}`: a fact the module asks for by name and never states.
//
// **A directory that states a path keeps it, and still answers `${dir:<id>}`.** That is the
// placement for an adopted machine: data that must sit where the predecessor already put it is
// declared with the path as the exception it is, and everything else in the module names it by
// id — so moving it later is one line, not a search.
//
// **The mesh's own files for a module are placed too** (novox/hq issue 174). What the mesh writes
// *for* a module — its sealed bus credential, its merged configuration, its bindings — is the
// mesh's plumbing, not the module's data, and sits under `<root>/mesh/<module>`. A directory
// saying `"place": "mesh"` is that place; the definition names the files beneath it by
// `${dir:<id>}` and states no path.
//
// **Resolved here, not on the machine.** The host receives concrete paths exactly as it always
// has; nothing new reaches it and it learns no field. Which also means a resolved path changing
// is a spec change like any other — and the spec comparison must see it (novox/hq issue 126).

// defaultDataRoot is where module data lands when a node states no root of its own.
const defaultDataRoot = "/var/lib"

// The two places a pathless directory may name, beside its own id.
const (
	// placeOwn is the assignment's own root, <root>/<module> — to-be 27's one directory per
	// assignment, which every other placed thing of the module sits beneath.
	placeOwn = "."
	// placeMesh is where the mesh keeps what it writes for the module, <root>/mesh/<module>.
	placeMesh = "mesh"
)

// dirRef is how a module names one of its placed directories: ${dir:<id>}.
var dirRef = regexp.MustCompile(`\$\{dir:([a-z0-9][a-z0-9-]*)\}`)

// dataRoot is the root this node keeps placed directories under.
func dataRoot(with Rendering) string {
	if root := strings.TrimRight(strings.TrimSpace(with.DataRoot), "/"); root != "" {
		return root
	}
	return defaultDataRoot
}

// dirsFor is every placed directory of a module, id → the path it resolves to on this node.
//
// A pathless directory saying `"place": "."` is the assignment's own root, <root>/<module>; one
// saying `"place": "mesh"` is the mesh's directory for the module, <root>/mesh/<module>; one
// saying neither is <root>/<module>/<id>. At most one of each place makes sense; nothing enforces
// one, because two ids resolving to one path is a mistake the module's own files make visible
// immediately.
//
// A stated path may itself begin with a placed reference — `${dir:mesh-state}/state` — and is
// filled after the directories it can name are resolved; one level, because a directory beneath
// a placed one is the whole of what an adopted layout needs (issue 174's `state` and `out`).
func dirsFor(m Manifest, with Rendering) map[string]string {
	dirs := map[string]string{}
	var beneath []map[string]any
	// The assignment's placement wins over both (novox/hq issue 153). Refused elsewhere when
	// malformed; here an invalid setting simply places nothing.
	placed, _ := Places(m, with.Settings[m.Module])
	for _, r := range m.Resources {
		if fmt.Sprint(r["type"]) != "directory" {
			continue
		}
		id := fmt.Sprint(r["id"])
		if p, said := placed[id]; said {
			dirs[id] = p.Path
			continue
		}
		if path, stated := r["path"].(string); stated && path != "" {
			if strings.HasPrefix(path, "${dir:") {
				beneath = append(beneath, r)
				continue
			}
			dirs[id] = strings.TrimRight(path, "/")
			continue
		}
		switch place, _ := r["place"].(string); place {
		case placeOwn:
			dirs[id] = dataRoot(with) + "/" + m.Module
		case placeMesh:
			dirs[id] = dataRoot(with) + "/mesh/" + m.Module
		default:
			dirs[id] = dataRoot(with) + "/" + m.Module + "/" + id
		}
	}
	for _, r := range beneath {
		path := strings.TrimRight(r["path"].(string), "/")
		// A reference to no directory is left as written and refused where the resource is
		// placed (dirInto), with the message that names what exists.
		filled, _ := dirFill(path, dirs, m.Module)
		dirs[fmt.Sprint(r["id"])] = filled
	}
	return dirs
}

// dirFill resolves every ${dir:…} in one string, or refuses a reference naming no directory.
func dirFill(s string, dirs map[string]string, module string) (string, error) {
	var missing error
	out := dirRef.ReplaceAllStringFunc(s, func(ref string) string {
		id := dirRef.FindStringSubmatch(ref)[1]
		path, has := dirs[id]
		if !has {
			missing = fmt.Errorf(
				"%s says ${dir:%s}, and %s declares no directory %q. It declares %s",
				module, id, module, id, orNothing(namesOfDirs(dirs)))
			return ref
		}
		return path
	})
	return out, missing
}

// placedManifest is the manifest with every path the mesh resolves already resolved: the maps
// naming where bindings, credentials and contributions land are filled against this node's
// placed directories, so everything downstream — the generated binding files, the sealed
// secrets, the grant directories — reads a concrete place and learns nothing new.
func placedManifest(m Manifest, with Rendering) (Manifest, error) {
	dirs := dirsFor(m, with)
	fillMap := func(in map[string]string) (map[string]string, error) {
		if len(in) == 0 {
			return in, nil
		}
		out := make(map[string]string, len(in))
		for key, value := range in {
			filled, err := dirFill(value, dirs, m.Module)
			if err != nil {
				return nil, err
			}
			out[key] = filled
		}
		return out, nil
	}
	var err error
	if m.Receives, err = fillMap(m.Receives); err != nil {
		return m, err
	}
	if m.Binds, err = fillMap(m.Binds); err != nil {
		return m, err
	}
	if m.Secrets, err = fillMap(m.Secrets); err != nil {
		return m, err
	}
	if len(m.OwnSecrets) > 0 {
		own := make(OwnSecrets, len(m.OwnSecrets))
		for name, s := range m.OwnSecrets {
			filled, err := dirFill(s.Path, dirs, m.Module)
			if err != nil {
				return m, err
			}
			own[name] = OwnSecret{Path: filled, Taken: s.Taken, IssuedBy: s.IssuedBy, Prompt: s.Prompt, Owner: s.Owner}
		}
		m.OwnSecrets = own
	}
	if m.Grants, err = fillMap(m.Grants); err != nil {
		return m, err
	}
	if len(m.SecretsMany) > 0 {
		many := make(map[string]map[string]string, len(m.SecretsMany))
		for to, locals := range m.SecretsMany {
			if many[to], err = fillMap(locals); err != nil {
				return m, err
			}
		}
		m.SecretsMany = many
	}
	return m, nil
}

// dirInto places a resource: a pathless directory is given the path the mesh resolved for it,
// and every ${dir:…} the resource carries — in its path, its content, its mounts, its
// environment and its env-files — becomes that path.
//
// A reference naming no directory of this module is refused. Left as written, the literal
// `${dir:x}` would reach the machine as a path, and the runtime would create and mount a
// directory called `${dir:x}` — real, wrong, and named after the mistake.
func dirInto(resource map[string]any, dirs map[string]string, module string) error {
	fill := func(s string) (string, error) { return dirFill(s, dirs, module) }

	if fmt.Sprint(resource["type"]) == "directory" {
		id := fmt.Sprint(resource["id"])
		if path, stated := resource["path"].(string); !stated || path == "" {
			resource["path"] = dirs[id]
		}
		// Said in the catalogue, not on the machine: the host parses strictly and knows no
		// such field — resolved, the place IS the path.
		delete(resource, "place")
	}

	var err error
	if path, ok := resource["path"].(string); ok {
		if resource["path"], err = fill(path); err != nil {
			return err
		}
	}
	if content, ok := resource["content"].(string); ok {
		if resource["content"], err = fill(content); err != nil {
			return err
		}
	}
	// Nested values are rebuilt, never written into: the resource is a shallow copy of the
	// manifest's own map, and the manifest is composed once per node — a fill written in place
	// would leave the first node's paths inside every later composition.
	if volumes, ok := resource["volumes"].([]any); ok {
		filled := make([]any, len(volumes))
		for i, v := range volumes {
			filled[i] = v
			if mount, ok := v.(string); ok {
				if filled[i], err = fill(mount); err != nil {
					return err
				}
			}
		}
		resource["volumes"] = filled
	}
	if env, ok := resource["env"].(map[string]any); ok {
		filled := make(map[string]any, len(env))
		for key, v := range env {
			filled[key] = v
			if value, ok := v.(string); ok {
				if filled[key], err = fill(value); err != nil {
					return err
				}
			}
		}
		resource["env"] = filled
	}
	if files, ok := resource["env-file"].([]any); ok {
		filled := make([]any, len(files))
		for i, v := range files {
			filled[i] = v
			if path, ok := v.(string); ok {
				if filled[i], err = fill(path); err != nil {
					return err
				}
			}
		}
		resource["env-file"] = filled
	}
	return nil
}

func namesOfDirs(dirs map[string]string) []string {
	var names []string
	for id := range dirs {
		names = append(names, fmt.Sprintf("%q", id))
	}
	sort.Strings(names)
	return names
}