// Copyright (c) 2026 Petr Balvín <opensource@petrbalvin.org> (https://petrbalvin.org)
// SPDX-License-Identifier: BSD-3-Clause

package lsp

import (
	"bytes"
	"encoding/json"
	"os"
	"path/filepath"
	"strings"
	"testing"
)

// diskWorkspace writes one helper file on disk and returns the workspace root
// and the caller document that references ·helper and ·late by symbol.
func diskWorkspace(t *testing.T) (root, callerURI string, caller string) {
	t.Helper()
	root = t.TempDir()
	helper := "TEXT \u00b7helper(SB), NOSPLIT, $0\n\tRET\n"
	if err := os.WriteFile(filepath.Join(root, "helper_amd64.s"), []byte(helper), 0o644); err != nil {
		t.Fatal(err)
	}
	caller = "TEXT \u00b7caller(SB), NOSPLIT, $0\n" +
		"\tCALL \u00b7helper(SB)\n" +
		"\tCALL \u00b7late(SB)\n" +
		"\tRET\n"
	callerURI = "file://" + root + "/caller_amd64.s"
	return root, callerURI, caller
}

// openCaller frames the initialize/didOpen scripting around the caller doc.
func openCaller(root, callerURI, caller string) string {
	return frame(1, "initialize", map[string]any{"rootUri": "file://" + root}) +
		frame(nil, "initialized", map[string]any{}) +
		frame(nil, "textDocument/didOpen", map[string]any{
			"textDocument": map[string]any{"uri": callerURI, "languageId": "gasm", "version": 1, "text": caller},
		})
}

// TestDefinitionReachesDiskFile checks that go-to-definition resolves a
// symbol to a workspace file the editor has never opened.
func TestDefinitionReachesDiskFile(t *testing.T) {
	root, callerURI, caller := diskWorkspace(t)
	in := openCaller(root, callerURI, caller) +
		frame(2, "textDocument/definition", map[string]any{
			"textDocument": map[string]any{"uri": callerURI},
			"position":     map[string]any{"line": 1, "character": 8}, // on helper in CALL ·helper(SB)
		}) + frame(nil, "exit", nil)
	msgs := run(t, in)
	resp := findByID(msgs, 2)
	if resp == nil {
		t.Fatal("no definition response")
	}
	var locs []Location
	if err := json.Unmarshal(mustResult(t, resp), &locs); err != nil {
		t.Fatal(err)
	}
	wantURI := fileToURI(filepath.Join(root, "helper_amd64.s"))
	if len(locs) != 1 || locs[0].URI != wantURI || locs[0].Range.Start.Line != 0 {
		t.Fatalf("definition = %+v, want the TEXT in %s line 0", locs, wantURI)
	}
}

// TestReferencesReachDiskFiles checks that find references collects the call
// site in the open document plus the definition in the unopened disk file.
func TestReferencesReachDiskFiles(t *testing.T) {
	root, callerURI, caller := diskWorkspace(t)
	in := openCaller(root, callerURI, caller) +
		frame(2, "textDocument/references", map[string]any{
			"textDocument": map[string]any{"uri": callerURI},
			"position":     map[string]any{"line": 1, "character": 8}, // on helper in CALL ·helper(SB)
			"context":      map[string]any{"includeDeclaration": true},
		}) + frame(nil, "exit", nil)
	msgs := run(t, in)
	resp := findByID(msgs, 2)
	if resp == nil {
		t.Fatal("no references response")
	}
	var locs []Location
	if err := json.Unmarshal(mustResult(t, resp), &locs); err != nil {
		t.Fatal(err)
	}
	byURI := map[string]int{}
	for _, l := range locs {
		byURI[l.URI]++
	}
	if byURI[callerURI] != 1 || byURI[fileToURI(filepath.Join(root, "helper_amd64.s"))] != 1 {
		t.Fatalf("references by uri = %v, want the call in the open document and the definition on disk", byURI)
	}
}

// TestWorkspaceSymbolsReachesDiskFiles checks the workspace symbol search
// against a file the editor has never opened.
func TestWorkspaceSymbolsReachesDiskFiles(t *testing.T) {
	root, callerURI, caller := diskWorkspace(t)
	in := openCaller(root, callerURI, caller) +
		frame(2, "workspace/symbol", map[string]any{"query": "helper"}) +
		frame(nil, "exit", nil)
	msgs := run(t, in)
	resp := findByID(msgs, 2)
	if resp == nil {
		t.Fatal("no workspace/symbol response")
	}
	var syms []WorkspaceSymbol
	if err := json.Unmarshal(mustResult(t, resp), &syms); err != nil {
		t.Fatal(err)
	}
	if len(syms) != 1 || syms[0].Name != "helper" ||
		syms[0].Location.URI != fileToURI(filepath.Join(root, "helper_amd64.s")) {
		t.Fatalf("symbols = %+v, want helper from the disk file", syms)
	}
}

// TestOpenBufferShadowsDiskFile pins the shadowing rule: when an open buffer
// carries unsaved edits, the answers come from the buffer, never from the
// stale disk copy.
func TestOpenBufferShadowsDiskFile(t *testing.T) {
	root, callerURI, caller := diskWorkspace(t)
	helperURI := "file://" + root + "/helper_amd64.s"
	// The buffer moved the definition to line 1; the disk copy has line 0.
	buffered := "\nTEXT \u00b7helper(SB), NOSPLIT, $0\n\tRET\n"
	in := openCaller(root, callerURI, caller) +
		frame(nil, "textDocument/didOpen", map[string]any{
			"textDocument": map[string]any{"uri": helperURI, "languageId": "gasm", "version": 1, "text": buffered},
		}) +
		frame(2, "textDocument/definition", map[string]any{
			"textDocument": map[string]any{"uri": callerURI},
			"position":     map[string]any{"line": 1, "character": 8},
		}) +
		frame(3, "textDocument/references", map[string]any{
			"textDocument": map[string]any{"uri": callerURI},
			"position":     map[string]any{"line": 1, "character": 8},
			"context":      map[string]any{"includeDeclaration": true},
		}) + frame(nil, "exit", nil)
	msgs := run(t, in)

	dresp := findByID(msgs, 2)
	if dresp == nil {
		t.Fatal("no definition response")
	}
	var locs []Location
	if err := json.Unmarshal(mustResult(t, dresp), &locs); err != nil {
		t.Fatal(err)
	}
	if len(locs) != 1 || locs[0].URI != helperURI || locs[0].Range.Start.Line != 1 {
		t.Fatalf("definition = %+v, want the buffered TEXT on line 1", locs)
	}

	rresp := findByID(msgs, 3)
	if rresp == nil {
		t.Fatal("no references response")
	}
	locs = nil
	if err := json.Unmarshal(mustResult(t, rresp), &locs); err != nil {
		t.Fatal(err)
	}
	if len(locs) != 2 {
		t.Fatalf("references = %+v, want the call and the buffered definition", locs)
	}
	for _, l := range locs {
		if l.URI == helperURI && l.Range.Start.Line != 1 {
			t.Errorf("reference in the opened file points at line %d, want the buffered line 1", l.Range.Start.Line)
		}
	}
}

// TestWatchedFileEventsUpdateIndex pins the one case a per-query refresh
// cannot cover: a file created after the build is unknown to the index until
// the client's watched-file event names it.  The steps run through dispatch
// directly, because the file must appear on disk between two requests.
func TestWatchedFileEventsUpdateIndex(t *testing.T) {
	root, callerURI, caller := diskWorkspace(t)
	latePath := filepath.Join(root, "late_amd64.s")
	lateURI := "file://" + latePath

	var buf bytes.Buffer
	srv := New(strings.NewReader(""), &buf)
	request := func(id int, method string, params any) *rpcMessage {
		t.Helper()
		raw, err := json.Marshal(params)
		if err != nil {
			t.Fatal(err)
		}
		var msgID *json.RawMessage
		if id > 0 {
			msgID = rawID(t, id)
		}
		srv.dispatch(&rpcMessage{ID: msgID, Method: method, Params: raw})
		msgs := readFrames(t, &buf)
		buf.Reset()
		if id > 0 {
			return findByID(msgs, id)
		}
		return nil
	}
	definitionOnLate := func(id int) []Location {
		t.Helper()
		resp := request(id, "textDocument/definition", map[string]any{
			"textDocument": map[string]any{"uri": callerURI},
			"position":     map[string]any{"line": 2, "character": 8}, // on late in CALL ·late(SB)
		})
		var locs []Location
		if err := json.Unmarshal(mustResult(t, resp), &locs); err != nil {
			t.Fatal(err)
		}
		return locs
	}

	request(1, "initialize", map[string]any{"rootUri": "file://" + root})
	request(0, "textDocument/didOpen", map[string]any{
		"textDocument": map[string]any{"uri": callerURI, "languageId": "gasm", "version": 1, "text": caller},
	})

	// The first request builds the index; the late file does not exist yet.
	if locs := definitionOnLate(2); len(locs) != 0 {
		t.Fatalf("definition before the file exists = %+v, want no result", locs)
	}

	if err := os.WriteFile(latePath, []byte("TEXT \u00b7late(SB), NOSPLIT, $0\n\tRET\n"), 0o644); err != nil {
		t.Fatal(err)
	}
	request(0, "workspace/didChangeWatchedFiles", map[string]any{
		"changes": []map[string]any{{"uri": lateURI, "type": fileCreated}},
	})
	if locs := definitionOnLate(4); len(locs) != 1 || locs[0].URI != fileToURI(latePath) {
		t.Fatalf("definition after the created event = %+v, want late_amd64.s", locs)
	}

	if err := os.Remove(latePath); err != nil {
		t.Fatal(err)
	}
	request(0, "workspace/didChangeWatchedFiles", map[string]any{
		"changes": []map[string]any{{"uri": lateURI, "type": fileDeleted}},
	})
	if locs := definitionOnLate(6); len(locs) != 0 {
		t.Fatalf("definition after the deleted event = %+v, want no result", locs)
	}
}

// TestFileToURIRoundTrip pins the URI encoding of the disk entries: the
// constructed URI decodes back to the path it came from.
func TestFileToURIRoundTrip(t *testing.T) {
	const path = "/tmp/Repositáře/kernels/helper.s"
	if got := uriPath(fileToURI(path)); got != path {
		t.Errorf("fileToURI round trip = %q, want %q", got, path)
	}
	if got := fileToURI("/plain/k.s"); got != "file:///plain/k.s" {
		t.Errorf("fileToURI plain = %q", got)
	}
}