// Package ui provides the browser-oriented Orchestra read model and controls.
package ui

import (
	"context"
	"encoding/json"
	"fmt"
	"hash/fnv"
	"net/http"
	"orchestra/internal/authz"
	"orchestra/internal/domain"
	"orchestra/internal/federation"
	"orchestra/internal/orchestrator"
	"orchestra/internal/store"
	"sort"
	"strings"
	"time"
)

type PendingApproval struct {
	Kind            string    `json:"kind"`
	Summary         string    `json:"summary"`
	Command         string    `json:"command,omitempty"`
	Diff            string    `json:"diff,omitempty"`
	PaneID          string    `json:"pane_id"`
	CaptureRevision uint64    `json:"capture_revision"`
	DetectedAt      time.Time `json:"detected_at"`
}
type Capture struct {
	TaskID    string    `json:"task_id"`
	Source    string    `json:"source"`
	Text      string    `json:"text"`
	Revision  uint64    `json:"revision"`
	At        time.Time `json:"at"`
	Truncated bool      `json:"truncated"`
}
type Action struct {
	ID      string   `json:"id"`
	Enabled bool     `json:"enabled"`
	Reason  string   `json:"reason,omitempty"`
	Needs   []string `json:"needs,omitempty"`
}
type Session struct {
	PaneID      string           `json:"pane_id,omitempty"`
	HarnessID   string           `json:"harness_id,omitempty"`
	AgentStatus string           `json:"agent_status,omitempty"`
	Blocker     string           `json:"blocker,omitempty"`
	LeaseUntil  *time.Time       `json:"lease_until,omitempty"`
	Capture     *Capture         `json:"capture,omitempty"`
	Approval    *PendingApproval `json:"pending_approval,omitempty"`
}
type TaskDetail struct {
	Task       domain.Task    `json:"task"`
	Events     []domain.Event `json:"events"`
	Session    *Session       `json:"session,omitempty"`
	HandoffRef string         `json:"handoff_ref,omitempty"`
	ReportRef  string         `json:"report_ref,omitempty"`
	Actions    []Action       `json:"actions"`
}
type Overview struct {
	Tasks     []domain.Task       `json:"tasks"`
	Workers   []federation.Worker `json:"workers"`
	Sessions  []Session           `json:"sessions"`
	UpdatedAt time.Time           `json:"updated_at"`
}

type Server struct {
	Store       *store.Store
	Workers     *federation.Registry
	Coordinator *orchestrator.Coordinator
	Route       func(domain.Event) error
}

func (s Server) capture(ctx context.Context, t domain.Task) (*Capture, error) {
	if t.State != domain.StateLeased || t.Lease == nil {
		return nil, nil
	}
	// B20: precedence is deliberate, not incidental. A published worker
	// capture means a registered worker owns that pane, and its revision is
	// the counter the worker's own staleness check compares against — so it
	// must win. Preferring the coordinator here (as this once did) handed
	// Queue a revision the worker could never match, and every such approval
	// resolved "stale" and silently never happened.
	if s.Workers != nil {
		if c, ok := s.Workers.Capture(t.Lease.HarnessID, t.ID); ok {
			return &Capture{TaskID: t.ID, Source: "worker", Text: c.Text, Revision: c.Revision, At: c.At}, nil
		}
	}
	if s.Coordinator != nil {
		text, err := s.Coordinator.Capture(ctx, t.ID, "recent")
		if err == nil {
			return &Capture{TaskID: t.ID, Source: "recent", Text: text, Revision: captureRevision(t.Lease.HarnessID, text), At: time.Now().UTC()}, nil
		}
	}
	return nil, fmt.Errorf("capture unavailable from owning worker")
}
func ParsePendingApproval(text, pane string, revision uint64, at time.Time) *PendingApproval {
	lines := strings.Split(text, "\n")
	low := strings.ToLower(text)
	if !strings.Contains(low, "permission required") && !strings.Contains(low, "approval required") && !strings.Contains(low, "allow this") {
		return nil
	}
	p := &PendingApproval{Kind: "unknown", Summary: "Harness permission prompt needs review", PaneID: pane, CaptureRevision: revision, DetectedAt: at}
	// OpenCode renders this exact three-choice selector and documents that
	// Enter confirms the initially selected "Allow once" action. It is not a
	// y/n prompt, so model it separately: grant is safe and bounded to once;
	// reject remains unavailable because the selected position is not exposed
	// in pane capture and Orchestra must not guess navigation keystrokes.
	if strings.Contains(low, "allow once") && strings.Contains(low, "allow always") && strings.Contains(low, "reject") && strings.Contains(low, "enter confirm") {
		p.Kind = "opencode_once"
		p.Summary = "Allow this command once"
	}
	for _, l := range lines {
		l = strings.TrimSpace(strings.TrimPrefix(strings.TrimSpace(l), "┃"))
		if strings.HasPrefix(l, "$ ") {
			if p.Kind == "unknown" {
				p.Kind = "shell"
			}
			p.Command = strings.TrimSpace(strings.TrimPrefix(l, "$ "))
			if p.Kind == "shell" {
				p.Summary = "Run shell command"
			}
			return p
		}
	}
	// Edits are intentionally only actionable when the harness gave an explicit diff.
	if i := strings.Index(text, "diff --git "); i >= 0 {
		p.Kind = "edit"
		p.Diff = text[i:]
		p.Summary = "Apply proposed edit"
	}
	return p
}
func (s Server) detail(ctx context.Context, id string) (TaskDetail, error) {
	t, ok := s.Store.Task(id)
	if !ok {
		return TaskDetail{}, domain.ErrNotFound
	}
	// Keep collection fields as JSON arrays for browser clients, including
	// older task records that genuinely have no retained events.
	d := TaskDetail{Task: t, Events: []domain.Event{}, Actions: actions(t)}
	for _, e := range s.Store.Events(0) {
		if e.TaskID != id {
			continue
		}
		d.Events = append(d.Events, e)
		var p struct {
			HandoffRef string `json:"handoff_ref"`
			ReportRef  string `json:"report_ref"`
		}
		_ = json.Unmarshal(e.Payload, &p)
		if p.HandoffRef != "" {
			d.HandoffRef = p.HandoffRef
		}
		if p.ReportRef != "" {
			d.ReportRef = p.ReportRef
		}
	}
	sort.Slice(d.Events, func(i, j int) bool { return d.Events[i].Seq < d.Events[j].Seq })
	if t.Lease != nil {
		session := &Session{HarnessID: t.Lease.HarnessID, LeaseUntil: &t.Lease.Until}
		if c, err := s.capture(ctx, t); err == nil && c != nil {
			session.Capture = c
			session.PaneID = capturePane(s, t, c)
			session.Approval = ParsePendingApproval(c.Text, session.PaneID, c.Revision, c.At)
		} else if err != nil {
			session.Blocker = "capture unavailable: " + err.Error()
		}
		d.Session = session
	} else if t.State == domain.StateBlocked {
		// A blocked task has no active lease by definition, but must retain its
		// last observed pane evidence instead of rendering an unexplained void.
		d.Session = &Session{PaneID: t.LastPaneID, HarnessID: t.LastHarness, AgentStatus: t.PaneState, Blocker: t.Blocker}
	}
	return d, nil
}

// captureRevision identifies *what the operator saw*, not when they saw it.
// B20: this was UnixNano, so it changed on every read and said nothing about
// whether the pane had changed. A content hash changes if and only if the
// text does, which is the only property any consumer of a revision wants.
func captureRevision(harness, text string) uint64 {
	h := fnv.New64a()
	_, _ = h.Write([]byte(harness))
	_, _ = h.Write([]byte{0})
	_, _ = h.Write([]byte(text))
	// 0 means "no revision" to federation.Queue; never collide with it.
	if v := h.Sum64(); v != 0 {
		return v
	}
	return 1
}

// capturePane resolves the pane the capture came from, following the same
// source precedence capture() used — asking the coordinator about a pane a
// worker owns (or vice versa) can return a pane the text never came from.
func capturePane(s Server, t domain.Task, c *Capture) string {
	if c.Source == "worker" && s.Workers != nil && t.Lease != nil {
		if remote, ok := s.Workers.Capture(t.Lease.HarnessID, t.ID); ok && remote.Revision == c.Revision {
			return remote.PaneID
		}
		return ""
	}
	if s.Coordinator != nil {
		if session, ok := s.Coordinator.Session(t.ID); ok {
			return session.PaneID
		}
	}
	return ""
}
func actions(t domain.Task) []Action {
	active := t.State == domain.StateLeased
	return []Action{{ID: "handoff", Enabled: active, Reason: "requires a live leased session"}, {ID: "release", Enabled: active, Needs: []string{"reason or handoff_ref"}}, {ID: "block", Enabled: active, Needs: []string{"blocker"}}, {ID: "complete", Enabled: active, Needs: []string{"report_ref", "receipt"}}}
}
func (s Server) Overview(ctx context.Context) Overview {
	// JSON null is not an empty collection to browser clients. In particular,
	// the shell renders the number of active sessions before any page-level
	// loading state, so a nil Sessions slice made an otherwise healthy empty
	// worker pool crash the entire SPA on `sessions.length`.
	tasks := s.Store.Tasks()
	if tasks == nil {
		tasks = []domain.Task{}
	}
	out := Overview{Tasks: tasks, Workers: []federation.Worker{}, Sessions: []Session{}, UpdatedAt: time.Now().UTC()}
	if s.Workers != nil {
		out.Workers = s.Workers.Snapshot()
	}
	for _, t := range out.Tasks {
		if t.Lease != nil {
			d, _ := s.detail(ctx, t.ID)
			if d.Session != nil {
				out.Sessions = append(out.Sessions, *d.Session)
			}
		}
	}
	return out
}
func writeJSON(w http.ResponseWriter, v any) {
	w.Header().Set("Content-Type", "application/json")
	_ = json.NewEncoder(w).Encode(v)
}
func (s Server) Handler() http.Handler {
	m := http.NewServeMux()
	m.HandleFunc("/v1/ui/overview", func(w http.ResponseWriter, r *http.Request) {
		if r.Method != http.MethodGet {
			http.Error(w, "method not allowed", 405)
			return
		}
		writeJSON(w, s.Overview(r.Context()))
	})
	m.HandleFunc("/v1/ui/tasks", func(w http.ResponseWriter, r *http.Request) {
		if r.Method != http.MethodPost {
			http.Error(w, "method not allowed", 405)
			return
		}
		var p map[string]any
		if json.NewDecoder(r.Body).Decode(&p) != nil {
			http.Error(w, "invalid json", 400)
			return
		}
		b, _ := json.Marshal(p)
		e := domain.Event{ID: domain.NewID(), Type: "TaskCreated", TaskID: domain.NewID(), Version: 1, Payload: b, Surface: string(authz.Web)}
		if err := s.Store.Append(e); err != nil {
			http.Error(w, err.Error(), 400)
			return
		}
		if s.Route != nil {
			_ = s.Route(e)
		}
		writeJSON(w, e)
	})
	m.HandleFunc("/v1/ui/tasks/", func(w http.ResponseWriter, r *http.Request) {
		rest := strings.TrimPrefix(r.URL.Path, "/v1/ui/tasks/")
		p := strings.Split(rest, "/")
		if len(p) == 1 && r.Method == http.MethodGet {
			d, err := s.detail(r.Context(), p[0])
			if err != nil {
				http.Error(w, "task not found", 404)
				return
			}
			writeJSON(w, d)
			return
		}
		if len(p) == 2 && p[1] == "capture" && r.Method == http.MethodGet {
			t, ok := s.Store.Task(p[0])
			if !ok {
				http.Error(w, "task not found", 404)
				return
			}
			c, err := s.capture(r.Context(), t)
			if err != nil || c == nil {
				http.Error(w, fmt.Sprintf("capture unavailable: %v", err), 503)
				return
			}
			writeJSON(w, c)
			return
		}
		if len(p) == 3 && p[1] == "actions" && r.Method == http.MethodPost {
			s.action(w, r, p[0], p[2])
			return
		}
		http.Error(w, "not found", 404)
	})
	m.HandleFunc("/v1/ui/artifacts/", func(w http.ResponseWriter, r *http.Request) {
		if r.Method != http.MethodGet {
			http.Error(w, "method not allowed", 405)
			return
		}
		ref := strings.TrimPrefix(r.URL.Path, "/v1/ui/artifacts/")
		if len(ref) != 64 {
			http.Error(w, "artifact ref required", 400)
			return
		}
		b, err := s.Store.Artifact(ref)
		if err != nil {
			http.Error(w, "artifact not found", 404)
			return
		}
		trim := strings.TrimSpace(string(b))
		if json.Valid(b) {
			w.Header().Set("Content-Type", "application/json")
		} else if strings.HasPrefix(trim, "#") || strings.Contains(trim, "\n#") {
			w.Header().Set("Content-Type", "text/markdown; charset=utf-8")
		} else {
			w.Header().Set("Content-Type", "text/plain; charset=utf-8")
		}
		_, _ = w.Write(b)
	})
	return m
}
func (s Server) action(w http.ResponseWriter, r *http.Request, id, action string) {
	t, ok := s.Store.Task(id)
	if !ok {
		http.Error(w, "task not found", 404)
		return
	}
	var body map[string]any
	_ = json.NewDecoder(r.Body).Decode(&body)
	var typ string
	switch action {
	case "grant_approval", "deny_approval":
		c, err := s.capture(r.Context(), t)
		if err != nil || c == nil {
			http.Error(w, "current capture unavailable", 503)
			return
		}
		pane := capturePane(s, t, c)
		approval := ParsePendingApproval(c.Text, pane, c.Revision, c.At)
		if approval == nil || approval.Kind == "unknown" || pane == "" {
			http.Error(w, "current prompt is not safely actionable", 409)
			return
		}
		if c.Source == "worker" {
			command, err := s.Workers.Queue(t.Lease.HarnessID, federation.Command{TaskID: id, Kind: action, PaneID: pane, CaptureRevision: c.Revision})
			if err != nil {
				http.Error(w, err.Error(), 409)
				return
			}
			// B19: the federated path used to return here, leaving the most
			// safety-critical operation in the system invisible in the event
			// log exactly when it crossed a machine boundary. The honest
			// event at this point is a *request* — the keystroke has only
			// been queued. The matching ApprovalGranted/ApprovalDenied is
			// appended when the worker reports the input was acknowledged
			// (see /v1/federation/commands/ in cmd/orchestra).
			payload, _ := json.Marshal(map[string]any{
				"subject_ref": command.ID, "options": []string{"grant_approval", "deny_approval"},
				"decision": action, "task_id": id, "worker": t.Lease.HarnessID,
				"pane_id": pane, "capture_revision": c.Revision,
			})
			e := domain.Event{ID: domain.NewID(), Type: "ApprovalRequested", TaskID: id, Version: t.Version + 1, Payload: payload, Surface: string(authz.Web)}
			if err := s.Store.Append(e); err != nil {
				// No audit trail, no approval. Resolve the queued command so
				// the worker never executes an unrecorded keystroke.
				_ = s.Workers.CompleteCommand(t.Lease.HarnessID, command.ID, "rejected", "audit append failed: "+err.Error())
				http.Error(w, "approval not recorded: "+err.Error(), 409)
				return
			}
			writeJSON(w, map[string]any{"command": command, "task": t})
			return
		}
		if s.Coordinator == nil {
			http.Error(w, "approval executor unavailable", 503)
			return
		}
		if err := s.Coordinator.RespondApproval(r.Context(), id, action == "grant_approval", c.Text); err != nil {
			http.Error(w, err.Error(), 409)
			return
		}
		typ := "ApprovalGranted"
		if action == "deny_approval" {
			typ = "ApprovalDenied"
		}
		payload, _ := json.Marshal(map[string]any{"subject_ref": id, "pane_id": pane, "capture_revision": c.Revision})
		e := domain.Event{ID: domain.NewID(), Type: typ, TaskID: id, Version: t.Version + 1, Payload: payload, Surface: string(authz.Web)}
		if err := s.Store.Append(e); err != nil {
			http.Error(w, err.Error(), 409)
			return
		}
		d, _ := s.detail(r.Context(), id)
		writeJSON(w, d)
		return
	case "handoff":
		if s.Coordinator == nil {
			http.Error(w, "live coordinator unavailable", 503)
			return
		}
		if err := s.Coordinator.RequestHandoff(r.Context(), id); err != nil {
			http.Error(w, err.Error(), 409)
			return
		}
		d, _ := s.detail(r.Context(), id)
		writeJSON(w, d)
		return
	case "release":
		typ = "TaskReleased"
	case "block":
		typ = "TaskBlocked"
	case "complete":
		typ = "TaskCompleted"
	default:
		http.Error(w, "unknown action", 404)
		return
	}
	if action == "block" {
		// A browser-created block is an explicit operator decision. Preserve
		// that fact even if its prose happens to contain a system keyword.
		body["block_reason"] = string(domain.BlockReasonOperator)
	}
	b, _ := json.Marshal(body)
	e := domain.Event{ID: domain.NewID(), Type: typ, TaskID: id, Version: t.Version + 1, Payload: b, Surface: string(authz.Web)}
	if err := s.Store.Append(e); err != nil {
		http.Error(w, err.Error(), 409)
		return
	}
	if s.Route != nil {
		_ = s.Route(e)
	}
	d, _ := s.detail(r.Context(), id)
	writeJSON(w, d)
}