package fs

// Shared utilities for the 9P namespace handlers.

import (
	"bytes"
	"fmt"
	"strings"
	"sync"

	"ollie/cmd/olliesrv/internal/agent"
	"ollie/cmd/olliesrv/internal/backend"
	"ollie/cmd/olliesrv/internal/session"
	"ollie/toolsrv/protocol"
	"ollie/virtfs"
)

// wireAgentEvents sets the state change callback on an agent.
func wireAgentEvents(sessID string, ag *agent.Agent) {
	ag.SetOnStateChange(func(agentID, state string) {
		session.PublishEvent("session."+sessID+".agent."+agentID+".state", state)
	})
}

// ctlCmd is one control verb: its name, a one-line description for the
// self-describing help listing, and its handler.
type ctlCmd struct {
	name string
	desc string
	fn   func([]string) ([]byte, error)
}

// dispatch routes a ctl write to a command by its first word. Reading the ctl
// file (empty write) or writing "help" returns the command listing. An unknown
// verb returns an error listing the valid verbs.
func dispatch(cmds []ctlCmd, data []byte) ([]byte, error) {
	input := strings.TrimSpace(string(data))
	if input == "" || input == "help" {
		var sb strings.Builder
		for _, c := range cmds {
			fmt.Fprintf(&sb, "%-16s %s\n", c.name, c.desc)
		}
		return []byte(sb.String()), nil
	}
	parts := strings.Fields(input)
	command := parts[0]
	args := parts[1:]
	if name, value, ok := strings.Cut(command, "="); ok {
		command = name
		args = append([]string{value}, args...)
	}
	for _, c := range cmds {
		if c.name == command {
			return c.fn(args)
		}
	}
	names := make([]string, len(cmds))
	for i, c := range cmds {
		names[i] = c.name
	}
	return nil, fmt.Errorf("unknown ctl command %q; valid: %s", command, strings.Join(names, ", "))
}

// stripMarkers removes [[[...]]] marker lines, source fence delimiter lines,
// and <context>...</context> blocks from raw chat data. Content inside fences
// is preserved — only the ``` lines themselves are stripped.
func stripMarkers(data []byte) []byte {
	var out []byte
	inContext := false
	for len(data) > 0 {
		nl := bytes.IndexByte(data, '\n')
		if nl < 0 {
			if !inContext {
				out = append(out, data...)
			}
			break
		}
		line := data[:nl+1]
		data = data[nl+1:]

		trimmed := bytes.TrimRight(line, "\n")

		// Handle <context> block start/end
		if bytes.Equal(bytes.TrimSpace(trimmed), []byte("<context>")) {
			inContext = true
			continue
		}
		if bytes.Equal(bytes.TrimSpace(trimmed), []byte("</context>")) {
			inContext = false
			continue
		}
		if inContext {
			continue
		}

		if len(trimmed) >= 7 && bytes.HasPrefix(trimmed, []byte("[[[")) && bytes.HasSuffix(trimmed, []byte("]]]")) {
			continue
		}
		stripped := bytes.TrimSpace(trimmed)
		if bytes.HasPrefix(stripped, []byte("```")) && !bytes.HasPrefix(stripped, []byte("````")) {
			continue
		}

		out = append(out, line...)
	}
	return out
}

// helpSpec stores the spec for help generation. Set during tree build.
var helpSpec *virtfs.FsNodeDecl

var (
	helpOnce sync.Once
	helpText string
	helpFn   = func() string {
		helpOnce.Do(func() {
			if helpSpec != nil {
				helpText = virtfs.GenerateHelp(*helpSpec)
			}
		})
		return helpText
	}
)

// agentNewRequest holds parsed results from an agent/new payload.
type agentNewRequest struct {
	Params      session.AgentParams
	Prompt      string
	ParentID    string
	ForkAt      int
	Timeout     int  // seconds; 0 = use default (600)
	MaxDepth    int  // max sub-agent depth; 0 = use default (1)
	MaxParallel *int // max concurrent children; nil = default (5), -1 = unlimited, 0 = disabled
}

// parseAgentNewRequest parses agent/new payloads in both formats:
//   - Newline-separated key=value (new format, supports multi-line values via \n escape)
//   - Space-separated key=value (legacy format from GUI)
//
// A bare word (no =) is treated as the profile name (legacy positional arg).
func parseAgentNewRequest(data []byte) agentNewRequest {
	s := strings.TrimSpace(string(data))
	if s == "" {
		return agentNewRequest{Params: session.AgentParams{Profile: "default"}}
	}

	var tokens []string
	if strings.Contains(s, "\n") {
		tokens = strings.Split(s, "\n")
	} else {
		tokens = strings.Fields(s)
	}

	r := agentNewRequest{Params: session.AgentParams{Profile: "default"}}
	for _, tok := range tokens {
		tok = strings.TrimSpace(tok)
		if tok == "" {
			continue
		}
		if k, v, ok := strings.Cut(tok, "="); ok {
			v = protocol.UnescapeValue(v)
			switch k {
			case "backend":
				r.Params.Backend = v
			case "model":
				r.Params.Model = v
			case "name":
				r.Params.Name = v
			case "remote":
				r.Params.Remote = v
			case "profile":
				r.Params.Profile = v
			case "prompt":
				r.Prompt = v
			case "parent":
				r.ParentID = v
			case "fork_at":
				fmt.Sscanf(v, "%d", &r.ForkAt)
			case "timeout":
				fmt.Sscanf(v, "%d", &r.Timeout)
			case "max_depth":
				fmt.Sscanf(v, "%d", &r.MaxDepth)
			case "max_parallel":
				var v2 int
				if _, err := fmt.Sscanf(v, "%d", &v2); err == nil {
					r.MaxParallel = &v2
				}
			}
		} else if r.Params.Profile == "default" {
			r.Params.Profile = tok
		}
	}
	return r
}

// messagesUpToTurn returns messages up to (and including) the Nth user turn.
// Turn 1 = first user message and everything before the second user message.
func messagesUpToTurn(msgs []backend.Message, n int) []backend.Message {
	userCount := 0
	for i, m := range msgs {
		if m.Role == "user" {
			userCount++
			if userCount > n {
				return msgs[:i]
			}
		}
	}
	return msgs
}