// Summary: LSP JSON-RPC handlers; implements core methods and integrates with the LLM client when enabled.
// TODO: Split this up into multiple smaller files.
package lsp

import (
	"encoding/json"
	"fmt"
	"hexai/internal/llm"
	"hexai/internal/logging"
	"strings"
	"time"
)

func (s *Server) handle(req Request) {
	if h, ok := s.handlers[req.Method]; ok {
		h(req)
		return
	}
	if len(req.ID) != 0 {
		s.reply(req.ID, nil, &RespError{Code: -32601, Message: fmt.Sprintf("method not found: %s", req.Method)})
	}
}

// handleInitialize moved to handlers_init.go

func (s *Server) llmRequestOpts() []llm.RequestOption {
	opts := []llm.RequestOption{llm.WithMaxTokens(s.maxTokens)}
	if s.codingTemperature != nil {
		opts = append(opts, llm.WithTemperature(*s.codingTemperature))
	}
	return opts
}

// instructionFromSelection extracts the first instruction from selection text.
// Preference order on each line: strict ;text; marker (no inner spaces), then
// a line comment (//, #, --). Returns the instruction string and the selection
// text cleaned of the matched instruction marker or comment.
func instructionFromSelection(sel string) (string, string) {
	lines := splitLines(sel)
	for idx, line := range lines {
		if instr, cleaned, ok := findFirstInstructionInLine(line); ok && strings.TrimSpace(instr) != "" {
			lines[idx] = cleaned
			return instr, strings.Join(lines, "\n")
		}
	}
	return "", sel
}

// findFirstInstructionInLine returns the earliest instruction marker on the
// line and the line with that marker removed. Supported markers, ordered by
// earliest byte offset in the line:
// - ;text; (strict, no space after first ';' or before last ';')
// - /* text */ (single-line only)
// - <!-- text --> (single-line only)
// - // text
// - # text
// - -- text
func findFirstInstructionInLine(line string) (instr string, cleaned string, ok bool) {
	type cand struct {
		start, end int
		text       string
	}
	cands := []cand{}
	if t, l, r, ok := findStrictSemicolonTag(line); ok {
		cands = append(cands, cand{start: l, end: r, text: t})
	}
	if i := strings.Index(line, "/*"); i >= 0 {
		if j := strings.Index(line[i+2:], "*/"); j >= 0 {
			start := i
			end := i + 2 + j + 2
			text := strings.TrimSpace(line[i+2 : i+2+j])
			cands = append(cands, cand{start: start, end: end, text: text})
		}
	}
	if i := strings.Index(line, "<!--"); i >= 0 {
		if j := strings.Index(line[i+4:], "-->"); j >= 0 {
			start := i
			end := i + 4 + j + 3
			text := strings.TrimSpace(line[i+4 : i+4+j])
			cands = append(cands, cand{start: start, end: end, text: text})
		}
	}
	if i := strings.Index(line, "//"); i >= 0 {
		cands = append(cands, cand{start: i, end: len(line), text: strings.TrimSpace(line[i+2:])})
	}
	if i := strings.Index(line, "#"); i >= 0 {
		cands = append(cands, cand{start: i, end: len(line), text: strings.TrimSpace(line[i+1:])})
	}
	if i := strings.Index(line, "--"); i >= 0 {
		cands = append(cands, cand{start: i, end: len(line), text: strings.TrimSpace(line[i+2:])})
	}
	if len(cands) == 0 {
		return "", line, false
	}
	// pick earliest start index
	best := cands[0]
	for _, c := range cands[1:] {
		if c.start >= 0 && (best.start < 0 || c.start < best.start) {
			best = c
		}
	}
	cleaned = strings.TrimRight(line[:best.start]+line[best.end:], " \t")
	return best.text, cleaned, true
}

// findStrictSemicolonTag finds ;text; with no space after first ';' and no space
// before the last ';' on the given line. Returns the text between semicolons,
// the start index of the opening ';', the end index just after the closing ';',
// and whether it was found.
func findStrictSemicolonTag(line string) (string, int, int, bool) {
	pos := 0
	for pos < len(line) {
		j := strings.Index(line[pos:], ";")
		if j < 0 {
			return "", 0, 0, false
		}
		j += pos
		// ensure single ';' (not ';;') and non-space after
		if j+1 >= len(line) || line[j+1] == ';' || line[j+1] == ' ' {
			pos = j + 1
			continue
		}
		k := strings.Index(line[j+1:], ";")
		if k < 0 {
			return "", 0, 0, false
		}
		closeIdx := j + 1 + k
		if closeIdx-1 < 0 || line[closeIdx-1] == ' ' {
			pos = closeIdx + 1
			continue
		}
		inner := strings.TrimSpace(line[j+1 : closeIdx])
		if inner == "" {
			pos = closeIdx + 1
			continue
		}
		end := closeIdx + 1
		return inner, j, end, true
	}
	return "", 0, 0, false
}

// diagnosticsInRange parses the CodeAction context and returns diagnostics
// that overlap the given selection range. If the context is missing or does
// not contain diagnostics, returns an empty slice.
// CodeAction-related handlers and helpers moved to handlers_codeaction.go

// extractRangeText returns the exact text within the given document range.
func extractRangeText(d *document, r Range) string {
	if r.Start.Line == r.End.Line {
		line := d.lines[r.Start.Line]
		if r.Start.Character < 0 {
			r.Start.Character = 0
		}
		if r.End.Character > len(line) {
			r.End.Character = len(line)
		}
		if r.Start.Character > r.End.Character {
			return ""
		}
		return line[r.Start.Character:r.End.Character]
	}
	var b strings.Builder
	// first line
	first := d.lines[r.Start.Line]
	if r.Start.Character < 0 {
		r.Start.Character = 0
	}
	if r.Start.Character > len(first) {
		r.Start.Character = len(first)
	}
	b.WriteString(first[r.Start.Character:])
	b.WriteString("\n")
	// middle lines
	for i := r.Start.Line + 1; i < r.End.Line; i++ {
		b.WriteString(d.lines[i])
		if i+1 <= r.End.Line {
			b.WriteString("\n")
		}
	}
	// last line
	last := d.lines[r.End.Line]
	if r.End.Character < 0 {
		r.End.Character = 0
	}
	if r.End.Character > len(last) {
		r.End.Character = len(last)
	}
	b.WriteString(last[:r.End.Character])
	return b.String()
}

// handleInitialized moved to handlers_init.go

// handleShutdown moved to handlers_init.go

// handleExit moved to handlers_init.go

// handleDidOpen moved to handlers_document.go

// handleDidChange moved to handlers_document.go

// handleDidClose moved to handlers_document.go

// handleCompletion moved to handlers_completion.go

func (s *Server) reply(id json.RawMessage, result any, err *RespError) {
	resp := Response{JSONRPC: "2.0", ID: id, Result: result, Error: err}
	s.writeMessage(resp)
}

// docBeforeAfter returns the full document text split at the given position.
// The returned strings are the text before the cursor (inclusive of anything
// left of the position) and the text after the cursor.
// docBeforeAfter moved to handlers_document.go

// extractTriggerInfo returns the LSP completion TriggerKind and TriggerCharacter
// if provided by the client; when absent it returns zeros.
// extractTriggerInfo moved to handlers_completion.go

// --- in-editor chat (";C ...") ---

// detectAndHandleChat scans the current document for any line that starts with
// ";C" and appears to be awaiting a response (i.e., followed by a blank line
// and no non-empty answer line yet). If found, it asks the LLM and inserts the
// answer below the blank line, leaving exactly one empty line between prompt
// and response.
// detectAndHandleChat moved to handlers_document.go

// applyChatEdits removes the triggering punctuation at end of the line and
// inserts two newlines followed by a new line with the response prefixed.
// applyChatEdits moved to handlers_document.go

// buildChatHistory walks upwards from the current line to collect the most recent
// Q/A pairs in the in-editor transcript. It returns messages in chronological order
// ending with the current user prompt. Limits to a small number of pairs to control tokens.
// buildChatHistory moved to handlers_document.go

// stripTrailingTrigger removes a single trailing punctuation from the set
// [?,!,:] or both semicolons if present at end, mirroring the inline trigger rules.
// stripTrailingTrigger moved to handlers_document.go

// clientApplyEdit sends a workspace/applyEdit request to the client.
// clientApplyEdit moved to handlers_document.go

// nextReqID returns a unique json.RawMessage id for server-initiated requests.
// nextReqID moved to handlers_document.go

// --- completion helpers ---

// buildDocString moved to handlers_completion.go

// logCompletionContext moved to handlers_completion.go

// tryLLMCompletion moved to handlers_completion.go

// parseManualInvoke inspects the LSP completion context and reports whether the user manually invoked completion.
// parseManualInvoke moved to handlers_completion.go

// shouldSuppressForChatTriggerEOL returns true when a chat trigger like ">" follows ?, !, :, or ; at EOL.
// shouldSuppressForChatTriggerEOL moved to handlers_completion.go

// prefixHeuristicAllows applies minimal prefix rules unless inlinePrompt or structural triggers apply.
// prefixHeuristicAllows moved to handlers_completion.go

// tryProviderNativeCompletion attempts provider-native completion and returns items when successful.
// tryProviderNativeCompletion moved to handlers_completion.go

// buildCompletionMessages constructs the LLM messages for completion.
// buildCompletionMessages moved to handlers_completion.go

// postProcessCompletion normalizes and deduplicates completion text and applies indentation rules.
// postProcessCompletion moved to handlers_completion.go

// busyCompletionItem builds a visible, non-inserting completion item indicating
// that an LLM request is already in flight.
func (s *Server) busyCompletionItem() CompletionItem {
	prov := ""
	model := ""
	if s.llmClient != nil {
		prov = s.llmClient.Name()
		model = s.llmClient.DefaultModel()
	}
	label := "Hexai: LLM busy"
	if prov != "" && model != "" {
		label += " (" + prov + ":" + model + ")"
	}
	return CompletionItem{
		Label:         label,
		Detail:        "Another request is running; only one is allowed concurrently",
		InsertText:    "",
		FilterText:    "",
		SortText:      "~~~~~busy", // float to top
		Documentation: "Hexai is processing a previous request. Please retry shortly.",
	}
}

func (s *Server) isLLMBusy() bool {
	s.mu.Lock()
	defer s.mu.Unlock()
	return s.llmBusy
}

func (s *Server) setLLMBusy(v bool) {
	s.mu.Lock()
	s.llmBusy = v
	s.mu.Unlock()
}

// --- small completion cache (last ~10 entries) ---

func (s *Server) completionCacheKey(p CompletionParams, above, current, below, funcCtx string, inParams bool, hasExtra bool, extraText string) string {
	// Normalize left-of-cursor by trimming trailing spaces/tabs
	idx := p.Position.Character
	if idx > len(current) {
		idx = len(current)
	}
	left := strings.TrimRight(current[:idx], " \t")
	right := ""
	if idx < len(current) {
		right = current[idx:]
	}
	prov := ""
	model := ""
	if s.llmClient != nil {
		prov = s.llmClient.Name()
		model = s.llmClient.DefaultModel()
	}
	temp := ""
	if s.codingTemperature != nil {
		temp = fmt.Sprintf("%.3f", *s.codingTemperature)
	}
	extra := ""
	if hasExtra {
		extra = strings.TrimSpace(extraText)
	}
	// Compose a key from essential context parts
	return strings.Join([]string{
		"v1", // version for future-proofing
		prov,
		model,
		temp,
		p.TextDocument.URI,
		fmt.Sprintf("%d:%d", p.Position.Line, len(left)),
		above,
		left,
		right,
		below,
		funcCtx,
		fmt.Sprintf("params=%t", inParams),
		extra,
	}, "\x1f") // use unit separator to avoid collisions
}

func (s *Server) completionCacheGet(key string) (string, bool) {
	s.mu.Lock()
	defer s.mu.Unlock()
	v, ok := s.compCache[key]
	if !ok {
		return "", false
	}
	// move to most-recent
	s.compCacheTouchLocked(key)
	return v, true
}

func (s *Server) completionCachePut(key, value string) {
	s.mu.Lock()
	defer s.mu.Unlock()
	if s.compCache == nil {
		s.compCache = make(map[string]string)
	}
	if _, exists := s.compCache[key]; !exists {
		s.compCacheOrder = append(s.compCacheOrder, key)
		s.compCache[key] = value
		if len(s.compCacheOrder) > 10 {
			// evict oldest
			old := s.compCacheOrder[0]
			s.compCacheOrder = s.compCacheOrder[1:]
			delete(s.compCache, old)
		}
		return
	}
	// update existing and mark most-recent
	s.compCache[key] = value
	s.compCacheTouchLocked(key)
}

func (s *Server) compCacheTouchLocked(key string) {
	// assumes s.mu is held
	// remove any existing occurrence of key in order slice
	idx := -1
	for i, k := range s.compCacheOrder {
		if k == key {
			idx = i
			break
		}
	}
	if idx >= 0 {
		s.compCacheOrder = append(append([]string{}, s.compCacheOrder[:idx]...), s.compCacheOrder[idx+1:]...)
	}
	s.compCacheOrder = append(s.compCacheOrder, key)
}

// isTriggerEvent returns true when the completion request appears to be caused
// by typing one of our configured trigger characters. It checks the LSP
// CompletionContext if provided and also falls back to inspecting the character
// immediately to the left of the cursor.
func (s *Server) isTriggerEvent(p CompletionParams, current string) bool {
	// 1) Inspect LSP completion context if present
	if p.Context != nil {
		var ctx struct {
			TriggerKind      int    `json:"triggerKind"`
			TriggerCharacter string `json:"triggerCharacter,omitempty"`
		}
		if raw, ok := p.Context.(json.RawMessage); ok {
			_ = json.Unmarshal(raw, &ctx)
		} else {
			b, _ := json.Marshal(p.Context)
			_ = json.Unmarshal(b, &ctx)
		}
		// If the line contains a bare ';;' (no ';;text;'), do not treat as a trigger source.
		if strings.Contains(current, ";;") && !hasDoubleSemicolonTrigger(current) {
			return false
		}
		// TriggerKind 1 = Invoked (manual) — always allow (unless bare ';;' above)
		if ctx.TriggerKind == 1 {
			return true
		}
		// TriggerKind 2 is TriggerCharacter per LSP spec
		if ctx.TriggerKind == 2 {
			if ctx.TriggerCharacter != "" {
				for _, c := range s.triggerChars {
					if c == ctx.TriggerCharacter {
						return true
					}
				}
				return false
			}
			// No character provided but reported as TriggerCharacter; be conservative
			return false
		}
		// For TriggerForIncomplete (3), require manual char check below
	}
	// 2) Fallback: check the character immediately prior to cursor
	idx := p.Position.Character
	if idx <= 0 || idx > len(current) {
		return false
	}
	// Bare ';;' should not trigger via fallback char either
	if strings.Contains(current, ";;") && !hasDoubleSemicolonTrigger(current) {
		return false
	}
	ch := string(current[idx-1])
	for _, c := range s.triggerChars {
		if c == ch {
			return true
		}
	}
	return false
}

func (s *Server) makeCompletionItems(cleaned string, inParams bool, current string, p CompletionParams, docStr string) []CompletionItem {
	te, filter := computeTextEditAndFilter(cleaned, inParams, current, p)
	rm := s.collectPromptRemovalEdits(p.TextDocument.URI)
	label := labelForCompletion(cleaned, filter)
	detail := "Hexai LLM completion"
	if s.llmClient != nil {
		detail = "Hexai " + s.llmClient.Name() + ":" + s.llmClient.DefaultModel()
	}
	return []CompletionItem{{
		Label:               label,
		Kind:                1,
		Detail:              detail,
		InsertTextFormat:    1,
		FilterText:          strings.TrimLeft(filter, " \t"),
		TextEdit:            te,
		AdditionalTextEdits: rm,
		SortText:            "0000",
		Documentation:       docStr,
	}}
}

// small helpers to keep tryLLMCompletion short
func (s *Server) incSentCounters(n int) {
	s.mu.Lock()
	s.llmReqTotal++
	s.llmSentBytesTotal += int64(n)
	s.mu.Unlock()
}

func (s *Server) incRecvCounters(n int) {
	s.mu.Lock()
	s.llmRespTotal++
	s.llmRespBytesTotal += int64(n)
	s.mu.Unlock()
}

func (s *Server) logLLMStats() {
	s.mu.RLock()
	avgSent := int64(0)
	if s.llmReqTotal > 0 {
		avgSent = s.llmSentBytesTotal / s.llmReqTotal
	}
	avgRecv := int64(0)
	if s.llmRespTotal > 0 {
		avgRecv = s.llmRespBytesTotal / s.llmRespTotal
	}
	reqs, sentTot, recvTot := s.llmReqTotal, s.llmSentBytesTotal, s.llmRespBytesTotal
	s.mu.RUnlock()
	mins := time.Since(s.startTime).Minutes()
	if mins <= 0 {
		mins = 0.001
	}
	rpm := float64(reqs) / mins
	sentPerMin := float64(sentTot) / mins
	recvPerMin := float64(recvTot) / mins
	logging.Logf("lsp ", "llm stats reqs=%d avg_sent=%d avg_recv=%d sent_total=%d recv_total=%d rpm=%.2f sent_per_min=%.0f recv_per_min=%.0f", reqs, avgSent, avgRecv, sentTot, recvTot, rpm, sentPerMin, recvPerMin)
}

// collectPromptRemovalEdits returns edits to remove all inline prompt markers.
// Supported form (inclusive):
//   - ";...;" where there is no space immediately after the first ';'
//     and no space immediately before the last ';'. An optional single space
//     after the trailing ';' is also removed for cleanliness.
//
// Multiple markers per line are supported.
func (s *Server) collectPromptRemovalEdits(uri string) []TextEdit {
	d := s.getDocument(uri)
	if d == nil || len(d.lines) == 0 {
		return nil
	}
	var edits []TextEdit
	for i, line := range d.lines {
		edits = append(edits, promptRemovalEditsForLine(line, i)...)
	}
	return edits
}

func promptRemovalEditsForLine(line string, lineNum int) []TextEdit {
	if hasDoubleSemicolonTrigger(line) {
		return []TextEdit{{Range: Range{Start: Position{Line: lineNum, Character: 0}, End: Position{Line: lineNum, Character: len(line)}}, NewText: ""}}
	}
	return collectSemicolonMarkers(line, lineNum)
}

func hasDoubleSemicolonTrigger(line string) bool {
	pos := 0
	for pos < len(line) {
		j := strings.Index(line[pos:], ";;")
		if j < 0 {
			return false
		}
		j += pos
		contentStart := j + 2
		if contentStart >= len(line) {
			return false // nothing after ';;'
		}
		// First content char cannot be space or another ';'
		first := line[contentStart]
		if first == ' ' || first == ';' {
			pos = contentStart + 1
			continue
		}
		// Require at least one content char before a closing ';'
		k := strings.Index(line[contentStart+1:], ";")
		if k < 0 {
			return false
		}
		closeIdx := contentStart + 1 + k
		// Disallow trailing space before closing ';'
		if closeIdx-1 >= 0 && line[closeIdx-1] == ' ' {
			pos = closeIdx + 1
			continue
		}
		return true
	}
	return false
}

func collectSemicolonMarkers(line string, lineNum int) []TextEdit {
	var edits []TextEdit
	startSemi := 0
	for startSemi < len(line) {
		j := strings.Index(line[startSemi:], ";")
		if j < 0 {
			break
		}
		j += startSemi
		k := strings.Index(line[j+1:], ";")
		if k < 0 {
			break
		}
		if j+1 >= len(line) || line[j+1] == ' ' {
			startSemi = j + 1
			continue
		}
		if line[j+1] == ';' {
			startSemi = j + 2
			continue
		}
		closeIdx := j + 1 + k
		if closeIdx-1 < 0 || line[closeIdx-1] == ' ' {
			startSemi = closeIdx + 1
			continue
		}
		if closeIdx-(j+1) < 1 {
			startSemi = closeIdx + 1
			continue
		}
		endChar := closeIdx + 1
		if endChar < len(line) && line[endChar] == ' ' {
			endChar++
		}
		edits = append(edits, TextEdit{Range: Range{Start: Position{Line: lineNum, Character: j}, End: Position{Line: lineNum, Character: endChar}}, NewText: ""})
		startSemi = endChar
	}
	return edits
}

func inParamList(current string, cursor int) bool {
	if !strings.Contains(current, "func ") {
		return false
	}
	open := strings.Index(current, "(")
	close := strings.Index(current, ")")
	return open >= 0 && cursor > open && (close == -1 || cursor <= close)
}

func buildPrompts(inParams bool, p CompletionParams, above, current, below, funcCtx string) (string, string) {
	if inParams {
		sys := "You are a code completion engine for function signatures. Return only the parameter list contents (without parentheses), no braces, no prose. Prefer idiomatic names and types."
		user := fmt.Sprintf("Cursor is inside the function parameter list. Suggest only the parameter list (no parentheses).\nFunction line: %s\nCurrent line (cursor at %d): %s", funcCtx, p.Position.Character, current)
		return sys, user
	}
	sys := "You are a terse code completion engine. Return only the code to insert, no surrounding prose or backticks. Only continue from the cursor; never repeat characters already present to the left of the cursor on the current line (e.g., if 'name :=' is already typed, only return the right-hand side expression)."
	user := fmt.Sprintf("Provide the next likely code to insert at the cursor.\nFile: %s\nFunction/context: %s\nAbove line: %s\nCurrent line (cursor at character %d): %s\nBelow line: %s\nOnly return the completion snippet.", p.TextDocument.URI, funcCtx, above, p.Position.Character, current, below)
	return sys, user
}

func computeTextEditAndFilter(cleaned string, inParams bool, current string, p CompletionParams) (*TextEdit, string) {
	if inParams {
		open := strings.Index(current, "(")
		close := strings.Index(current, ")")
		if open >= 0 {
			left := open + 1
			right := len(current)
			if close >= 0 && close >= left {
				right = close
			}
			if p.Position.Character < right {
				right = p.Position.Character
			}
			te := &TextEdit{Range: Range{Start: Position{Line: p.Position.Line, Character: left}, End: Position{Line: p.Position.Line, Character: right}}, NewText: cleaned}
			var filter string
			if left >= 0 && right >= left && right <= len(current) {
				filter = strings.TrimLeft(current[left:right], " \t")
			}
			return te, filter
		}
	}
	startChar := computeWordStart(current, p.Position.Character)
	te := &TextEdit{Range: Range{Start: Position{Line: p.Position.Line, Character: startChar}, End: Position{Line: p.Position.Line, Character: p.Position.Character}}, NewText: cleaned}
	filter := strings.TrimLeft(current[startChar:p.Position.Character], " \t")
	return te, filter
}

func computeWordStart(current string, at int) int {
	if at > len(current) {
		at = len(current)
	}
	for at > 0 {
		ch := current[at-1]
		if (ch >= 'a' && ch <= 'z') || (ch >= 'A' && ch <= 'Z') || (ch >= '0' && ch <= '9') || ch == '_' {
			at--
			continue
		}
		break
	}
	return at
}

func isIdentChar(ch byte) bool {
	return (ch >= 'a' && ch <= 'z') || (ch >= 'A' && ch <= 'Z') || (ch >= '0' && ch <= '9') || ch == '_'
}

// lineHasInlinePrompt returns true if the line contains an inline strict
// semicolon marker ;text; (no spaces at boundaries) or a double-semicolon
// pattern recognized by hasDoubleSemicolonTrigger.
func lineHasInlinePrompt(line string) bool {
	if _, _, _, ok := findStrictSemicolonTag(line); ok {
		return true
	}
	return hasDoubleSemicolonTrigger(line)
}

// leadingIndent returns the run of leading spaces/tabs from the provided line.
func leadingIndent(line string) string {
	i := 0
	for i < len(line) {
		if line[i] == ' ' || line[i] == '\t' {
			i++
			continue
		}
		break
	}
	if i == 0 {
		return ""
	}
	return line[:i]
}

// applyIndent prefixes each non-empty line of suggestion with the given indent
// unless it already starts with that indent.
func applyIndent(indent, suggestion string) string {
	if indent == "" || suggestion == "" {
		return suggestion
	}
	lines := splitLines(suggestion)
	for i, ln := range lines {
		if strings.TrimSpace(ln) == "" {
			continue
		}
		if strings.HasPrefix(ln, indent) {
			continue
		}
		lines[i] = indent + ln
	}
	return strings.Join(lines, "\n")
}

// isBareDoubleSemicolon reports whether the line contains a standalone
// double-semicolon marker with no inline content (";;" possibly with only
// whitespace after it). It explicitly excludes the valid form ";;text;".
func isBareDoubleSemicolon(line string) bool {
	t := strings.TrimSpace(line)
	if !strings.Contains(t, ";;") {
		return false
	}
	if hasDoubleSemicolonTrigger(t) {
		return false
	}
	if strings.HasPrefix(t, ";;") {
		rest := strings.TrimSpace(t[2:])
		// Bare if nothing follows or only semicolons/spaces remain without closing pattern
		if rest == "" || rest == ";" {
			return true
		}
	}
	return false
}

// stripDuplicateAssignmentPrefix removes a duplicated assignment prefix (e.g.,
// "name :=") from the beginning of the model suggestion when that same prefix
// already appears immediately to the left of the cursor on the current line.
// Also handles simple '=' assignments.
func stripDuplicateAssignmentPrefix(prefixBeforeCursor, suggestion string) string {
	s2 := strings.TrimLeft(suggestion, " \t")
	// Prefer := if present at end of prefix
	if idx := strings.LastIndex(prefixBeforeCursor, ":="); idx >= 0 && idx+2 <= len(prefixBeforeCursor) {
		// Ensure only spaces follow in prefix (cursor at end of prefix segment)
		tail := prefixBeforeCursor[idx+2:]
		if strings.TrimSpace(tail) == "" {
			// Move left to include identifier and spaces
			start := idx - 1
			for start >= 0 && (isIdentChar(prefixBeforeCursor[start]) || prefixBeforeCursor[start] == ' ' || prefixBeforeCursor[start] == '\t') {
				start--
			}
			start++
			seg := strings.TrimRight(prefixBeforeCursor[start:idx+2], " \t")
			if strings.HasPrefix(s2, seg) {
				return strings.TrimLeft(s2[len(seg):], " \t")
			}
		}
	}
	// Fallback to plain '=' if present
	if idx := strings.LastIndex(prefixBeforeCursor, "="); idx >= 0 {
		if !(idx > 0 && prefixBeforeCursor[idx-1] == ':') { // not := (handled above)
			tail := prefixBeforeCursor[idx+1:]
			if strings.TrimSpace(tail) == "" {
				start := idx - 1
				for start >= 0 && (isIdentChar(prefixBeforeCursor[start]) || prefixBeforeCursor[start] == ' ' || prefixBeforeCursor[start] == '\t') {
					start--
				}
				start++
				seg := strings.TrimRight(prefixBeforeCursor[start:idx+1], " \t")
				if strings.HasPrefix(s2, seg) {
					return strings.TrimLeft(s2[len(seg):], " \t")
				}
			}
		}
	}
	return suggestion
}

// stripDuplicateGeneralPrefix removes any already-typed prefix that the model repeated
// at the beginning of its suggestion. It compares the entire text to the left of the
// cursor (prefixBeforeCursor) against the suggestion, trimming whitespace appropriately,
// and strips the longest sensible overlap. This prevents cases like:
//
//	prefix:    "func New "
//	suggestion:"func New() *Type"
//
// resulting in duplicates like "func New func New() *Type".
func stripDuplicateGeneralPrefix(prefixBeforeCursor, suggestion string) string {
	if suggestion == "" {
		return suggestion
	}
	s := strings.TrimLeft(suggestion, " \t")
	p := strings.TrimRight(prefixBeforeCursor, " \t")
	// Exact prefix overlap: remove the full typed prefix
	if p != "" && strings.HasPrefix(s, p) {
		return strings.TrimLeft(s[len(p):], " \t")
	}
	// Otherwise, try the longest token-aligned suffix of p that prefixes s
	// Prefer boundaries where the char before the suffix is not an identifier char
	for k := len(p) - 1; k > 0; k-- {
		if !isIdentBoundary(p[k-1]) {
			continue
		}
		suf := strings.TrimLeft(p[k:], " \t")
		if suf == "" {
			continue
		}
		if strings.HasPrefix(s, suf) {
			return strings.TrimLeft(s[len(suf):], " \t")
		}
	}
	return suggestion
}

func isIdentBoundary(ch byte) bool {
	return !((ch >= 'a' && ch <= 'z') || (ch >= 'A' && ch <= 'Z') || (ch >= '0' && ch <= '9') || ch == '_')
}

// stripCodeFences removes surrounding Markdown code fences from a model
// response when the entire output is wrapped, e.g. starting with "```go" or
// "```" and ending with "```". It returns the inner content unchanged.
func stripCodeFences(s string) string {
	t := strings.TrimSpace(s)
	if t == "" {
		return t
	}
	lines := splitLines(t)
	// find first and last non-empty lines
	start := 0
	for start < len(lines) && strings.TrimSpace(lines[start]) == "" {
		start++
	}
	end := len(lines) - 1
	for end >= 0 && strings.TrimSpace(lines[end]) == "" {
		end--
	}
	if start >= len(lines) || end < 0 || start > end {
		return t
	}
	first := strings.TrimSpace(lines[start])
	last := strings.TrimSpace(lines[end])
	if strings.HasPrefix(first, "```") && last == "```" && end > start {
		inner := strings.Join(lines[start+1:end], "\n")
		return inner
	}
	return t
}

// stripInlineCodeSpan returns only the contents of the first inline backtick
// code span if present, e.g., "some text `x := y()` more" -> "x := y()".
// If no matching pair of backticks exists, it returns the input unchanged.
// This is intended for code completion responses where the model may wrap a
// small snippet in single backticks among prose.
func stripInlineCodeSpan(s string) string {
	t := strings.TrimSpace(s)
	if t == "" {
		return t
	}
	i := strings.IndexByte(t, '`')
	if i < 0 {
		return t
	}
	jrel := strings.IndexByte(t[i+1:], '`')
	if jrel < 0 {
		return t
	}
	j := i + 1 + jrel
	return t[i+1 : j]
}

func labelForCompletion(cleaned, filter string) string {
	label := trimLen(firstLine(cleaned))
	if filter != "" && !strings.HasPrefix(strings.ToLower(label), strings.ToLower(filter)) {
		return filter
	}
	return label
}

func (s *Server) fallbackCompletionItems(docStr string) []CompletionItem {
	return []CompletionItem{{
		Label:         "hexai-complete",
		Kind:          1,
		Detail:        "dummy completion",
		InsertText:    "hexai",
		SortText:      "9999",
		Documentation: docStr,
	}}
}