package catalogue

import (
	"bytes"
	"encoding/json"
	"fmt"
	"maps"
	"slices"
)

// A Verb is one tool a role serves: its name, what it does, and the schema of its arguments and of
// its answer (novox/hq ADR 0132, design 33 §2).
//
// **A name alone is not callable by something that has never seen the mesh before**, which is the
// whole population a tool surface exists for. So a seat's protocol carries the definition, in the
// form an agent protocol already uses — a JSON schema for the input — so nothing translates between
// a seat's idea of an argument and the caller's.
//
// A manifest may still write a bare verb name (`"serves": ["price"]`); that is a Verb with only a
// name, and the module's runtime answers `tools` with the rest. The two forms read into one type so
// nothing downstream cares which was written.
type Verb struct {
	Name        string         `json:"name"`
	Description string         `json:"description,omitempty"`
	Input       map[string]any `json:"input,omitempty"`
	Output      map[string]any `json:"output,omitempty"`
	// Optional marks a verb added to a mesh seat whose holder lives in another repository (design 33 §7,
	// additive within a version): a holder that serves it is accepted, and one that does not yet still
	// holds the seat. Without it the addition would be a deadlock — this controller refusing the holder that
	// does not serve the verb, the controller before it refusing the holder that does — and every check of
	// the catalogue between the two would fail on a module nobody touched. Once every holder serves it,
	// the mark is removed and the verb is a condition of holding like the rest. Never stored or said: the
	// seat set's protocol is the compiled one.
	Optional bool `json:"-"`
	// Replaces are the shell commands this verb is the mesh's way to do, each as it is typed —
	// `journalctl`, `systemctl restart` — so the agent finds the verb by the command it would have run
	// and is told to call it instead (novox/hq ADR 0245): the mesh MCP server's search matches them, the agent's
	// instructions list them, and the guard on its shell names the verb when it refuses a work-around.
	// A command line is matched by its words in order, the first being the command's name; `edit
	// /etc/hosts` and `HOSTALIASES` name the guard's two local work-arounds for a mesh name.
	Replaces []string `json:"replaces,omitempty"`
}

func (v *Verb) UnmarshalJSON(raw []byte) error {
	trimmed := bytes.TrimSpace(raw)
	if len(trimmed) > 0 && trimmed[0] == '"' {
		var name string
		if err := json.Unmarshal(trimmed, &name); err != nil {
			return err
		}
		*v = Verb{Name: name}
		return nil
	}
	// Strictly, like the manifest around it: a misspelt key in a tool's definition would otherwise
	// describe a tool nobody can call and refuse nothing.
	type plain Verb
	var p plain
	decoder := json.NewDecoder(bytes.NewReader(trimmed))
	decoder.DisallowUnknownFields()
	if err := decoder.Decode(&p); err != nil {
		return fmt.Errorf("a served verb is a name or {name, description, input, output}: %w", typedUnknown(err))
	}
	if p.Name == "" {
		return fmt.Errorf("a served verb has no name: %s", trimmed)
	}
	*v = Verb(p)
	return nil
}

// VerbNames are the names alone, for the grants and the checks that care about nothing else.
func VerbNames(verbs []Verb) []string {
	out := make([]string, 0, len(verbs))
	for _, v := range verbs {
		out = append(out, v.Name)
	}
	return out
}

// schema is a JSON schema for an object of string properties, which is every argument the verbs
// above take. Kept small on purpose: a schema an agent cannot read is a tool it cannot call. The
// switches are the properties that are "true" or "false" and nothing else, said in the schema as an
// enum so a caller sees it and the verb can refuse any other word rather than read it as false.
//
// **The schema is the whole of what a verb takes** (novox/hq issue 244): an argument it does not
// name is refused when the verb is called, never passed over.
// withObject adds to a verb's input s the property name, an object of the string fields given, each required.
func withObject(s map[string]any, name, description string, fields map[string]string) map[string]any {
	inner := schema(fields, slices.Sorted(maps.Keys(fields)))
	inner["description"], inner["additionalProperties"] = description, false
	s["properties"].(map[string]any)[name] = inner
	return s
}

func schema(properties map[string]string, required []string, switches ...string) map[string]any {
	isSwitch := map[string]bool{}
	for _, s := range switches {
		if _, declared := properties[s]; !declared {
			panic("a switch that is not a property: " + s)
		}
		isSwitch[s] = true
	}
	props := map[string]any{}
	for name, description := range properties {
		p := map[string]any{"type": "string", "description": description}
		if isSwitch[name] {
			p["enum"] = []string{"true", "false"}
		}
		props[name] = p
	}
	out := map[string]any{"type": "object", "properties": props}
	if len(required) > 0 {
		out["required"] = required
	}
	return out
}

// listed makes the named properties of a schema lists of text: a caller gives them as a JSON array (or, as
// any argument, one text separated by commas).
func listed(in map[string]any, names ...string) map[string]any {
	props, _ := in["properties"].(map[string]any)
	for _, n := range names {
		p, _ := props[n].(map[string]any)
		if p == nil {
			panic("a list that is not a property: " + n)
		}
		props[n] = map[string]any{"type": "array", "items": map[string]any{"type": "string"},
			"description": p["description"]}
	}
	return in
}

// unpromised is what a claim says it serves and the seat's protocol never promised.
func unpromised(serves []string, promised []Verb) []string {
	has := map[string]bool{}
	for _, v := range promised {
		has[v.Name] = true
	}
	var extra []string
	for _, s := range serves {
		if !has[s] {
			extra = append(extra, s)
		}
	}
	return extra
}

// unservedVerbs is what a seat promises and a claimant's offer for it does not answer.
func unservedVerbs(tools []string, promised []Verb) []string {
	has := map[string]bool{}
	for _, t := range tools {
		has[t] = true
	}
	var missing []string
	for _, v := range promised {
		if !has[v.Name] && !v.Optional {
			missing = append(missing, v.Name)
		}
	}
	return missing
}