// Package capturehttp is the REST adapter for the capture use-case: the
// POST /capture door (#53). It is deliberately thin — authenticate, derive
// the trust-zone origin from the authenticated principal, decode the
// request, call capture.Service, map the receipt to an HTTP status. No
// business logic lives here; the I1 gate, validation, and orchestration
// are all in the use-case.
package capturehttp

import (
	"context"
	"crypto/subtle"
	"encoding/json"
	"errors"
	"io"
	"net/http"
	"strings"

	"github.com/mathiasbq/hyperguild/ingestion/internal/capture"
)

// Validator validates a Bearer JWT and returns its subject. The chassis
// *auth.JWTValidator satisfies it (including its nil-receiver "disabled"
// behaviour), and tests can substitute a fake without a live JWKS.
type Validator interface {
	Validate(ctx context.Context, rawToken string) (string, error)
}

// Handler serves POST /capture.
type Handler struct {
	svc             *capture.Service
	validator       Validator // nil ⇒ JWT auth disabled
	staticToken     string    // "" ⇒ static auth disabled
	staticPrincipal string    // principal name attributed to static-token callers
	resolver        OriginResolver
}

// New constructs a capture HTTP handler. staticToken callers are
// attributed to staticPrincipal (a sovereign homelab identity); JWT
// callers are attributed to their token subject.
func New(svc *capture.Service, validator Validator, staticToken, staticPrincipal string, resolver OriginResolver) *Handler {
	if staticPrincipal == "" {
		staticPrincipal = "local-cli"
	}
	return &Handler{
		svc:             svc,
		validator:       validator,
		staticToken:     staticToken,
		staticPrincipal: staticPrincipal,
		resolver:        resolver,
	}
}

// wire types — the POST /capture request body.
type request struct {
	Context  contextBody   `json:"context"`
	Insights []insightBody `json:"insights"`
	Tickets  []ticketBody  `json:"tickets"`
	Summary  *summaryBody  `json:"summary,omitempty"`
	DryRun   bool          `json:"dry_run"`
}

type contextBody struct {
	Harness        string `json:"harness"`
	SessionRef     string `json:"session_ref"`
	Fidelity       string `json:"fidelity"`
	Actor          string `json:"actor"`
	Classification string `json:"classification"`
}

type insightBody struct {
	Text          string `json:"text"`
	Wing          string `json:"wing"`
	Hall          string `json:"hall"`
	SupersedeSlug string `json:"supersede_slug,omitempty"`
}

type ticketBody struct {
	Repo   string `json:"repo"`
	Action string `json:"action"`
	Number int    `json:"number,omitempty"`
	Title  string `json:"title,omitempty"`
	Body   string `json:"body,omitempty"`
}

type summaryBody struct {
	Title        string   `json:"title"`
	Body         string   `json:"body"`
	ReposTouched []string `json:"repos_touched,omitempty"`
}

// ServeHTTP authenticates, derives origin, runs the use-case, and maps the
// result to an HTTP status.
func (h *Handler) ServeHTTP(w http.ResponseWriter, r *http.Request) {
	principal, viaStatic, ok := Authenticate(r, h.staticToken, h.staticPrincipal, h.validator)
	if !ok {
		http.Error(w, "unauthorized", http.StatusUnauthorized)
		return
	}

	body, err := io.ReadAll(r.Body)
	if err != nil {
		writeJSON(w, http.StatusBadRequest, map[string]string{"error": "read body"})
		return
	}
	in, err := DecodeRequest(body)
	if err != nil {
		writeJSON(w, http.StatusBadRequest, map[string]string{"error": "invalid JSON"})
		return
	}
	// Principal and origin are server-derived — overwrite anything the
	// caller may have tried to put in the body.
	in.Context.Principal = principal
	in.Context.Origin = h.resolver.Resolve(principal, viaStatic)

	rec, err := h.svc.Capture(r.Context(), in)
	switch {
	case errors.Is(err, capture.ErrSovereigntyRefused):
		writeJSON(w, http.StatusForbidden, map[string]string{"error": err.Error()})
		return
	case errors.Is(err, capture.ErrAuditUnavailable):
		// I5 refusal: confidential + audit sink down, or the all-tiers floor.
		writeJSON(w, http.StatusServiceUnavailable, map[string]string{"error": err.Error()})
		return
	case err != nil:
		// Pre-write validation failure (fail-closed).
		writeJSON(w, http.StatusBadRequest, map[string]string{"error": err.Error()})
		return
	}
	writeJSON(w, statusFor(rec), rec)
}

// Authenticate mirrors the chassis Bearer precedence (static token wins,
// then Dex JWT) and returns the resolved principal plus whether the static
// path was taken — the chassis middleware hides both, and capture (REST or
// MCP) needs them to derive the trust-zone origin. ok is false when no
// credential matched.
func Authenticate(r *http.Request, staticToken, staticPrincipal string, validator Validator) (principal string, viaStatic, ok bool) {
	raw, found := strings.CutPrefix(r.Header.Get("Authorization"), "Bearer ")
	if !found || raw == "" {
		return "", false, false
	}
	if staticToken != "" && subtle.ConstantTimeCompare([]byte(raw), []byte(staticToken)) == 1 {
		return staticPrincipal, true, true
	}
	if validator != nil {
		if sub, err := validator.Validate(r.Context(), raw); err == nil && sub != "" {
			return sub, false, true
		}
	}
	return "", false, false
}

// DecodeRequest parses a capture request body into a CaptureInput. Shared
// by the REST adapter and the MCP capture tool so the wire shape has one
// definition. Principal and Origin are NOT set here — the caller sets them
// from the authenticated identity.
func DecodeRequest(data []byte) (capture.CaptureInput, error) {
	var b request
	if err := json.Unmarshal(data, &b); err != nil {
		return capture.CaptureInput{}, err
	}
	return b.toInput(), nil
}

func (b request) toInput() capture.CaptureInput {
	in := capture.CaptureInput{
		Context: capture.CaptureContext{
			Harness:        b.Context.Harness,
			SessionRef:     b.Context.SessionRef,
			Fidelity:       b.Context.Fidelity,
			Actor:          b.Context.Actor,
			Classification: b.Context.Classification,
		},
		DryRun: b.DryRun,
	}
	for _, i := range b.Insights {
		in.Insights = append(in.Insights, capture.Insight{
			Text: i.Text, Wing: i.Wing, Hall: i.Hall, SupersedeSlug: i.SupersedeSlug,
		})
	}
	for _, t := range b.Tickets {
		in.Tickets = append(in.Tickets, capture.Ticket{
			Repo: t.Repo, Action: t.Action, Number: t.Number, Title: t.Title, Body: t.Body,
		})
	}
	if b.Summary != nil {
		in.Summary = &capture.Summary{
			Title: b.Summary.Title, Body: b.Summary.Body, ReposTouched: b.Summary.ReposTouched,
		}
	}
	return in
}

// statusFor maps a receipt to an HTTP status: 200 all-ok (or dry-run),
// 207 partial, 502 everything-failed.
func statusFor(rec capture.CaptureReceipt) int {
	if rec.DryRun {
		return http.StatusOK
	}
	var ok, fail int
	for _, i := range rec.Insights {
		count(&ok, &fail, i.OK)
	}
	for _, t := range rec.Tickets {
		count(&ok, &fail, t.OK)
	}
	if rec.Summary != nil {
		count(&ok, &fail, rec.Summary.OK)
	}
	switch {
	case fail == 0:
		return http.StatusOK
	case ok == 0:
		return http.StatusBadGateway // every persistence attempt failed
	default:
		return http.StatusMultiStatus // 207: partial success
	}
}

func count(ok, fail *int, isOK bool) {
	if isOK {
		*ok++
	} else {
		*fail++
	}
}

func writeJSON(w http.ResponseWriter, status int, v any) {
	w.Header().Set("Content-Type", "application/json")
	w.WriteHeader(status)
	_ = json.NewEncoder(w).Encode(v)
}