package app

import (
	"fmt"
	"regexp"
	"strings"
	"sync"
	"syscall"
	"time"

	"github.com/harrybrwn/patterm/internal/mcp"
	"github.com/harrybrwn/patterm/internal/policy"
	"github.com/harrybrwn/patterm/internal/preset"
	"github.com/harrybrwn/patterm/internal/scratchpad"
)

// attentionSink is implemented by uiState to surface
// request_human_attention notifications.
type attentionSink interface {
	notifyAttention(childID, reason string)
}

// toolHost adapts the running session + scratchpad store to the MCP
// ToolHost interface. SPEC §7 tools route through here.
type toolHost struct {
	sess       *Session
	pads       *scratchpad.Store
	launcher   *Launcher
	presets    preset.Set
	policy     *policy.Policy
	sizeMu     sync.Mutex
	defaultRow uint16
	defaultCol uint16

	attention attentionSink

	// timersMu guards timers.
	timersMu  sync.Mutex
	nextTimer int
}

func (h *toolHost) SetSize(cols, rows uint16) {
	h.sizeMu.Lock()
	defer h.sizeMu.Unlock()
	h.defaultCol = cols
	h.defaultRow = rows
}

func (h *toolHost) size() (uint16, uint16) {
	h.sizeMu.Lock()
	defer h.sizeMu.Unlock()
	return h.defaultCol, h.defaultRow
}

func newToolHost(sess *Session, pads *scratchpad.Store, launcher *Launcher, presets preset.Set, pol *policy.Policy, cols, rows uint16) *toolHost {
	return &toolHost{
		sess:       sess,
		pads:       pads,
		launcher:   launcher,
		presets:    presets,
		policy:     pol,
		defaultCol: cols,
		defaultRow: rows,
	}
}

// PolicyCheck — SPEC §9 hook. Lets an orchestrator ask whether a
// prompt-looking string is safe to auto-answer.
func (h *toolHost) PolicyCheck(prompt string) string {
	if h.policy == nil {
		return string(policy.Unknown)
	}
	return string(h.policy.Should(prompt))
}

// Children — SPEC §7 list_children. The idle_ms field gives the
// orchestrator the SPEC §11 done-signal without needing to poll bytes.
func (h *toolHost) Children() []mcp.ChildInfo {
	cs := h.sess.Children()
	out := make([]mcp.ChildInfo, 0, len(cs))
	for _, c := range cs {
		out = append(out, mcp.ChildInfo{
			ID:       c.ID,
			Name:     c.Name,
			Type:     string(c.Kind),
			Status:   string(c.Status()),
			ExitCode: c.ExitCode(),
			IdleMS:   c.IdleMS(),
			ParentID: c.ParentID,
		})
	}
	return out
}

func (h *toolHost) Spawn(callerID, name string, argv []string, shell bool) (mcp.ChildInfo, error) {
	if shell && len(argv) > 0 {
		argv = []string{"sh", "-lc", strings.Join(argv, " ")}
	}
	parent := callerID
	cols, rows := h.size()
	c, err := h.sess.Spawn(name, KindProcess, argv, nil, cols, rows, parent)
	if err != nil {
		return mcp.ChildInfo{}, err
	}
	return mcp.ChildInfo{
		ID:       c.ID,
		Name:     c.Name,
		Type:     string(c.Kind),
		Status:   string(c.Status()),
		ParentID: c.ParentID,
	}, nil
}

func (h *toolHost) SpawnAgent(callerID, presetName, displayName, initialPrompt string) (mcp.ChildInfo, error) {
	var p *preset.Preset
	for _, ap := range h.presets.Agents {
		if ap.Name == presetName {
			p = ap
			break
		}
	}
	if p == nil {
		return mcp.ChildInfo{}, fmt.Errorf("unknown agent preset %q", presetName)
	}
	if displayName == "" {
		displayName = presetName
	}
	c, err := h.launcher.LaunchAgent(p, displayName, initialPrompt, callerID)
	if err != nil {
		return mcp.ChildInfo{}, err
	}
	return mcp.ChildInfo{
		ID:       c.ID,
		Name:     c.Name,
		Type:     string(c.Kind),
		Status:   string(c.Status()),
		ParentID: c.ParentID,
	}, nil
}

// ReadOutput — SPEC §7. Grid uses the emulator's PlainText; stream uses
// the per-child ring buffer. For grid reads on agents we apply the
// preset's chrome_trim_hints (SPEC §10) so banners/input-box noise
// doesn't pollute orchestrator parsing.
func (h *toolHost) ReadOutput(callerID, childID, mode string, sinceOffset int) (string, int, error) {
	c := h.sess.FindChild(childID)
	if c == nil {
		return "", 0, fmt.Errorf("no such child %q", childID)
	}
	switch mode {
	case "grid":
		txt, err := c.em.PlainText()
		if err != nil {
			return "", 0, err
		}
		if c.Kind == KindAgent {
			txt = applyChromeTrim(txt, h.chromeHintsFor(c.Name))
		}
		return txt, 0, nil
	case "stream":
		b, off := c.StreamRead(int64(sinceOffset))
		return string(b), int(off), nil
	default:
		return "", 0, fmt.Errorf("unknown read_output mode %q", mode)
	}
}

func (h *toolHost) chromeHintsFor(presetName string) []string {
	for _, p := range h.presets.Agents {
		if p.Name == presetName {
			return p.ChromeTrimHints
		}
	}
	return nil
}

// applyChromeTrim deletes every line that matches any of the given
// regexes. Compiled regexes are cached per call; the agent preset list
// is small enough that recompilation cost is negligible.
func applyChromeTrim(txt string, hints []string) string {
	if len(hints) == 0 {
		return txt
	}
	res := make([]*regexp.Regexp, 0, len(hints))
	for _, h := range hints {
		re, err := regexp.Compile(h)
		if err != nil {
			continue
		}
		res = append(res, re)
	}
	if len(res) == 0 {
		return txt
	}
	out := make([]string, 0, 64)
	for _, line := range strings.Split(txt, "\n") {
		drop := false
		for _, re := range res {
			if re.MatchString(line) {
				drop = true
				break
			}
		}
		if !drop {
			out = append(out, line)
		}
	}
	return strings.Join(out, "\n")
}

func (h *toolHost) SendInput(callerID, childID string, payload []byte, appendNewline bool) error {
	if appendNewline {
		payload = append(payload, '\n')
	}
	c := h.sess.FindChild(childID)
	if c == nil {
		return fmt.Errorf("no such child %q", childID)
	}
	if c.Status() != StatusRunning {
		return fmt.Errorf("child %q is %s", childID, c.Status())
	}
	return c.InjectAsOrchestrator(payload)
}

func (h *toolHost) Kill(callerID, childID string, sig syscall.Signal) error {
	return h.sess.Kill(childID, sig)
}

// SendMessageTo — SPEC §7 + §8. Injects "[orchestrator] <msg>\n" into
// the target's PTY.
func (h *toolHost) SendMessageTo(callerID, targetID, message string) error {
	target := h.sess.FindChild(targetID)
	if target == nil {
		return fmt.Errorf("no such child %q", targetID)
	}
	line := "[orchestrator] " + message + "\n"
	return target.InjectAsOrchestrator([]byte(line))
}

// ReportToParent — SPEC §8. Injects "[sub-agent:<name>] <msg>\n" into
// the calling agent's parent pane.
func (h *toolHost) ReportToParent(callerID, message string) error {
	caller := h.sess.FindChild(callerID)
	if caller == nil {
		return fmt.Errorf("caller %q not known to patterm", callerID)
	}
	if caller.ParentID == "" {
		return fmt.Errorf("caller %q has no parent", callerID)
	}
	parent := h.sess.FindChild(caller.ParentID)
	if parent == nil {
		return fmt.Errorf("parent %q gone", caller.ParentID)
	}
	line := fmt.Sprintf("[sub-agent:%s] %s\n", caller.Name, message)
	return parent.InjectAsOrchestrator([]byte(line))
}

// TimerWait — SPEC §7. Returns immediately with a timer_id. After
// seconds elapse, injects "[system] Your timer [<label>] has completed.\n"
// into the calling agent's pane.
func (h *toolHost) TimerWait(callerID string, seconds float64, label string) (string, error) {
	caller := h.sess.FindChild(callerID)
	if caller == nil {
		return "", fmt.Errorf("caller %q not known to patterm", callerID)
	}
	h.timersMu.Lock()
	h.nextTimer++
	id := fmt.Sprintf("t%d", h.nextTimer)
	h.timersMu.Unlock()
	if label == "" {
		label = id
	}
	go func() {
		time.Sleep(time.Duration(seconds * float64(time.Second)))
		if caller.Status() != StatusRunning {
			return
		}
		line := fmt.Sprintf("[system] Your timer [%s] has completed.\n", label)
		_ = caller.InjectAsOrchestrator([]byte(line))
	}()
	return id, nil
}

// WaitForPattern — SPEC §7. Polls the child's plain-text grid at ~50ms
// until the regex matches or the timeout expires.
func (h *toolHost) WaitForPattern(callerID, childID, pattern string, timeoutSeconds float64) (bool, string, error) {
	c := h.sess.FindChild(childID)
	if c == nil {
		return false, "", fmt.Errorf("no such child %q", childID)
	}
	re, err := regexp.Compile(pattern)
	if err != nil {
		return false, "", fmt.Errorf("regex: %w", err)
	}
	deadline := time.Now().Add(time.Duration(timeoutSeconds * float64(time.Second)))
	tick := time.NewTicker(50 * time.Millisecond)
	defer tick.Stop()
	for {
		txt, err := c.em.PlainText()
		if err == nil {
			if m := re.FindString(txt); m != "" {
				return true, m, nil
			}
		}
		if time.Now().After(deadline) {
			return false, "", nil
		}
		<-tick.C
		if c.Status() != StatusRunning {
			return false, "", nil
		}
	}
}

func (h *toolHost) RequestHumanAttention(callerID, childID, reason string) error {
	if h.attention != nil {
		h.attention.notifyAttention(childID, reason)
	}
	return nil
}

func (h *toolHost) Scratchpads() *scratchpad.Store {
	return h.pads
}

// ResolveCallerIdentity maps the per-spawn identity token back to a
// child ID so the tools above can use it as a parent pointer / inject
// target.
func (h *toolHost) ResolveCallerIdentity(identity string) string {
	c := h.sess.FindChildByIdentity(identity)
	if c == nil {
		return ""
	}
	return c.ID
}