package hooks

import (
	"encoding/json"
	"io"
	"os"
	"strings"

	"github.com/zzet/gortex/internal/modelhint"
)

// Mode selects the posture of the Claude Code PreToolUse / PostToolUse
// integration. Two modes are supported:
//
//   - ModeDeny (default, "deny"): the PreToolUse hook actively denies
//     whole-file Grep / Glob / Read of indexed source and points the
//     agent at the equivalent Gortex graph tools. The agent learns by
//     friction. No PostToolUse hook is registered.
//
//   - ModeEnrich ("enrich"): the PreToolUse hook never denies — it only
//     emits soft `additionalContext` guidance — and a PostToolUse hook
//     augments the tool's actual output with graph context (enclosing
//     symbols, file metadata, callers). Easier onboarding for teams that
//     don't want their agent stopped mid-flow; the graph value still
//     lands, just adjacent to the raw output rather than as a redirect.
//
//   - ModeConsultUnlock ("consult-unlock"): the PreToolUse hook denies
//     Read / Grep / Glob fallback only until the agent has queried the
//     Gortex graph at least once this session. The first `mcp__gortex__*`
//     tool call flips a per-session marker; from then on the deny is
//     downgraded to soft `additionalContext` (same as ModeEnrich). The
//     posture nudges the agent to consult the graph before falling back
//     to raw file reads, then gets out of the way.
//
//   - ModeAdaptiveNudge ("nudge"): instead of denying every fallback
//     call, the hook counts consecutive non-symbolic tool calls per
//     session and soft-denies once when the streak crosses a threshold,
//     then resets — so the reminder fires once per burst and the very
//     next call proceeds. A symbolic / `mcp__gortex__*` call resets the
//     streak to zero.
//
// The modes co-exist by selection — a user picks one per install via
// `gortex install --hook-mode=<mode>`. Switching modes is a single
// re-install; the Claude Code adapter rewrites the hook command and
// adds / removes the PostToolUse entry to match.
type Mode int

const (
	// ModeDeny preserves the legacy "redirect by deny" behavior.
	ModeDeny Mode = iota
	// ModeEnrich augments tool output rather than denying it.
	ModeEnrich
	// ModeConsultUnlock denies fallback reads until the agent has
	// consulted the Gortex graph once, then downgrades to soft context.
	ModeConsultUnlock
	// ModeAdaptiveNudge soft-denies once per burst of non-symbolic
	// fallback calls rather than denying every call.
	ModeAdaptiveNudge
)

// ParseMode resolves the string form into a Mode. Empty / unknown
// values fall through to ModeDeny so unset environments keep the
// established behavior.
func ParseMode(s string) Mode {
	switch strings.ToLower(strings.TrimSpace(s)) {
	case "enrich":
		return ModeEnrich
	case "consult-unlock":
		return ModeConsultUnlock
	case "nudge", "adaptive-nudge":
		return ModeAdaptiveNudge
	default:
		return ModeDeny
	}
}

// String renders the mode in its canonical lower-case form. Useful for
// logging and for round-tripping the value through the `--mode` flag.
func (m Mode) String() string {
	switch m {
	case ModeEnrich:
		return "enrich"
	case ModeConsultUnlock:
		return "consult-unlock"
	case ModeAdaptiveNudge:
		return "nudge"
	default:
		return "deny"
	}
}

// Run reads a single hook payload from stdin, peeks at hook_event_name,
// and dispatches to the right handler. This is the single entry point
// `.claude/settings.local.json` should register via `gortex hook`.
//
// Any error in reading or parsing results in a silent no-op — hooks
// must never block Claude Code's normal flow.
func Run(port int, mode Mode) {
	data, err := io.ReadAll(os.Stdin)
	if err != nil {
		return
	}

	var peek struct {
		HookEventName string `json:"hook_event_name"`
	}
	if err := json.Unmarshal(data, &peek); err != nil {
		return
	}

	switch peek.HookEventName {
	case "PreToolUse":
		captureModelHint(data)
		runPreToolUse(data, port, mode)
	case "PostToolUse":
		runPostToolUse(data)
	case "PreCompact":
		runPreCompact(data, port)
	case "Stop":
		runPostTask(data, port)
	case "SessionStart":
		captureModelHint(data)
		runSessionStart(data)
	case "UserPromptSubmit":
		runUserPromptSubmit(data)
	}
}

// captureModelHint extracts the active LLM model from a hook payload and
// records it through the model-hint bridge, so the (separate-process)
// daemon's savings recorder can attribute per-call token savings to the
// model that drove the call. The model arrives two ways: SessionStart
// carries it as a top-level `model` field, while PreToolUse does not —
// there we read the most recent assistant turn from the session
// transcript, which also catches a mid-session `/model` switch. Entirely
// best-effort: any gap leaves the model unknown and savings stay
// provider-neutral.
func captureModelHint(data []byte) {
	var in struct {
		CWD            string `json:"cwd"`
		Model          string `json:"model"`
		TranscriptPath string `json:"transcript_path"`
	}
	if json.Unmarshal(data, &in) != nil {
		return
	}
	model := strings.TrimSpace(in.Model)
	if model == "" && in.TranscriptPath != "" {
		model = modelFromTranscript(in.TranscriptPath)
	}
	if model == "" {
		return
	}
	modelhint.Write(in.CWD, model, "claude-code")
}