module builder

import os
import hash
import time
import rand
import strings
import v.util
import v.pref
import v.vcache

pub fn (mut b Builder) rebuild_modules() {
	if !b.pref.use_cache || b.pref.build_mode == .build_module {
		return
	}
	all_files := b.parsed_files.map(it.path)
	$if trace_invalidations ? {
		eprintln('> rebuild_modules all_files: ${all_files}')
	}
	invalidations := b.find_invalidated_modules_by_files(all_files)
	$if trace_invalidations ? {
		eprintln('> rebuild_modules invalidations: ${invalidations}')
	}
	if invalidations.len > 0 {
		vexe := pref.vexe_path()
		for imp in invalidations {
			b.v_build_module(vexe, imp)
		}
	}
}

pub fn (mut b Builder) find_invalidated_modules_by_files(all_files []string) []string {
	util.timing_start('${@METHOD} source_hashing')
	mut new_hashes := map[string]string{}
	mut old_hashes := map[string]string{}
	mut sb_new_hashes := strings.new_builder(1024)
	//
	mut cm := vcache.new_cache_manager(all_files)
	sold_hashes := cm.load('.hashes', 'all_files') or { ' ' }
	// eprintln(sold_hashes)
	sold_hashes_lines := sold_hashes.split('\n')
	for line in sold_hashes_lines {
		if line.len == 0 {
			continue
		}
		x := line.split(' ')
		chash := x[0]
		cpath := x[1]
		old_hashes[cpath] = chash
	}
	// eprintln('old_hashes: $old_hashes')
	for cpath in all_files {
		ccontent := util.read_file(cpath) or { '' }
		chash := hash.sum64_string(ccontent, 7).hex_full()
		new_hashes[cpath] = chash
		sb_new_hashes.write_string(chash)
		sb_new_hashes.write_u8(` `)
		sb_new_hashes.write_string(cpath)
		sb_new_hashes.write_u8(`\n`)
	}
	snew_hashes := sb_new_hashes.str()
	// eprintln('new_hashes: $new_hashes')
	// eprintln('> new_hashes != old_hashes: ' + ( old_hashes != new_hashes ).str())
	// eprintln(snew_hashes)
	cm.save('.hashes', 'all_files', snew_hashes) or {}
	util.timing_measure('${@METHOD} source_hashing')

	mut invalidations := []string{}
	if new_hashes != old_hashes {
		util.timing_start('${@METHOD} rebuilding')
		// eprintln('> b.mod_invalidates_paths: $b.mod_invalidates_paths')
		// eprintln('> b.mod_invalidates_mods: $b.mod_invalidates_mods')
		// eprintln('> b.path_invalidates_mods: $b.path_invalidates_mods')
		$if trace_invalidations ? {
			for k, v in b.mod_invalidates_paths {
				mut m := map[string]bool{}
				for mm in b.mod_invalidates_mods[k] {
					m[mm] = true
				}
				eprintln('> module `${k}` invalidates: ${m.keys()}')
				for fpath in v {
					eprintln('         ${fpath}')
				}
			}
		}
		mut invalidated_paths := map[string]int{}
		mut invalidated_mod_paths := map[string]int{}
		for npath, nhash in new_hashes {
			if npath !in old_hashes {
				invalidated_paths[npath]++
				continue
			}
			if old_hashes[npath] != nhash {
				invalidated_paths[npath]++
				continue
			}
		}
		for opath, ohash in old_hashes {
			if opath !in new_hashes {
				invalidated_paths[opath]++
				continue
			}
			if new_hashes[opath] != ohash {
				invalidated_paths[opath]++
				continue
			}
		}
		$if trace_invalidations ? {
			eprintln('invalidated_paths: ${invalidated_paths}')
		}
		mut rebuild_everything := false
		for cycle := 0; true; cycle++ {
			$if trace_invalidations ? {
				eprintln('> cycle: ${cycle} | invalidated_paths: ${invalidated_paths}')
			}
			mut new_invalidated_paths := map[string]int{}
			for npath, _ in invalidated_paths {
				invalidated_mods := b.path_invalidates_mods[npath]
				if invalidated_mods == ['main'] {
					continue
				}
				if 'builtin' in invalidated_mods {
					// When `builtin` is invalid, there is no point in
					// extracting a finer grained dependency resolution
					// of the dependencies any more. Instead, just rebuild
					// every module.
					rebuild_everything = true
					break
				}
				for imod in invalidated_mods {
					if imod == 'main' {
						continue
					}
					for np in b.mod_invalidates_paths[imod] {
						new_invalidated_paths[np]++
					}
				}
				$if trace_invalidations ? {
					eprintln('> npath -> invalidated_mods | ${npath} -> ${invalidated_mods}')
				}
				mpath := os.dir(npath)
				invalidated_mod_paths[mpath]++
			}
			if rebuild_everything {
				break
			}
			if new_invalidated_paths.len == 0 {
				break
			}
			invalidated_paths = new_invalidated_paths.clone()
		}
		if rebuild_everything {
			invalidated_mod_paths = {}
			for npath, _ in new_hashes {
				mpath := os.dir(npath)
				pimods := b.path_invalidates_mods[npath]
				if pimods == ['main'] {
					continue
				}
				invalidated_mod_paths[mpath]++
			}
		}
		$if trace_invalidations ? {
			eprintln('invalidated_mod_paths: ${invalidated_mod_paths}')
			eprintln('rebuild_everything: ${rebuild_everything}')
		}
		if invalidated_mod_paths.len > 0 {
			impaths := invalidated_mod_paths.keys()
			for imp in impaths {
				invalidations << imp
			}
		}
		util.timing_measure('${@METHOD} rebuilding')
	}
	return invalidations
}

fn (mut b Builder) v_build_module(vexe string, imp_path string) {
	pwd := os.getwd()
	defer {
		os.chdir(pwd) or {}
	}
	// do run `v build-module x` always in main vfolder; x can be a relative path
	vroot := os.dir(vexe)
	os.chdir(vroot) or {}
	boptions := b.pref.build_options.join(' ')
	rebuild_cmd := '${os.quoted_path(vexe)} ${boptions} build-module ${os.quoted_path(imp_path)}'
	vcache.dlog('| Builder.' + @FN, 'vexe: ${vexe} | imp_path: ${imp_path} | rebuild_cmd: ${rebuild_cmd}')
	$if trace_v_build_module ? {
		eprintln('> Builder.v_build_module: ${rebuild_cmd}')
	}
	os.system(rebuild_cmd)
}

fn (mut b Builder) rebuild_cached_module(vexe string, imp_path string) string {
	res := b.pref.cache_manager.mod_exists(imp_path, '.o', imp_path) or {
		if b.pref.is_verbose {
			println('Cached ${imp_path} .o file not found... Building .o file for ${imp_path}')
		}
		b.v_build_module(vexe, imp_path)
		rebuilt_o := b.pref.cache_manager.mod_exists(imp_path, '.o', imp_path) or {
			panic('could not rebuild cache module for ${imp_path}, error: ${err.msg()}')
		}
		return rebuilt_o
	}
	return res
}

fn (mut b Builder) handle_usecache(vexe string) {
	if !b.pref.use_cache || b.pref.build_mode == .build_module {
		return
	}
	mut libs := []string{} // builtin.o os.o http.o etc
	mut built_modules := []string{}
	builtin_obj_path := b.rebuild_cached_module(vexe, 'vlib/builtin')
	libs << builtin_obj_path
	for ast_file in b.parsed_files {
		if b.pref.is_test && ast_file.mod.name != 'main' {
			imp_path := b.find_module_path(ast_file.mod.name, ast_file.path) or {
				verror('cannot import module "${ast_file.mod.name}" (not found)')
				break
			}
			obj_path := b.rebuild_cached_module(vexe, imp_path)
			libs << obj_path
			built_modules << ast_file.mod.name
		}
		for imp_stmt in ast_file.imports {
			imp := imp_stmt.mod
			// strconv is already imported inside builtin, so skip generating its object file
			// TODO: in case we have other modules with the same name, make sure they are vlib
			// is this even doing anything?
			if util.module_is_builtin(imp) {
				continue
			}
			if imp in built_modules {
				continue
			}
			if util.should_bundle_module(imp) {
				continue
			}
			// The problem is cmd/v is in module main and imports
			// the relative module named help, which is built as cmd.v.help not help
			// currently this got this working by building into main, see ast.FnDecl in cgen
			if imp == 'help' {
				continue
			}
			imp_path := b.find_module_path(imp, ast_file.path) or {
				verror('cannot import module "${imp}" (not found)')
				break
			}
			obj_path := b.rebuild_cached_module(vexe, imp_path)
			libs << obj_path
			built_modules << imp
		}
	}
	b.ccoptions.post_args << libs
}

pub fn (mut b Builder) should_rebuild() bool {
	mut exe_name := b.pref.out_name
	$if windows {
		exe_name += '.exe'
	}
	if !os.is_file(exe_name) {
		return true
	}
	if !b.pref.is_crun {
		return true
	}
	mut v_program_files := []string{}
	is_file := os.is_file(b.pref.path)
	is_dir := os.is_dir(b.pref.path)
	if is_file {
		v_program_files << b.pref.path
	} else if is_dir {
		v_program_files << b.v_files_from_dir(b.pref.path)
	}
	v_program_files.sort() // ensure stable keys for the dependencies cache
	b.crun_cache_keys = v_program_files
	b.crun_cache_keys << exe_name
	// just check the timestamps for now:
	exe_stamp := os.file_last_mod_unix(exe_name)
	source_stamp := most_recent_timestamp(v_program_files)
	if exe_stamp <= source_stamp {
		return true
	}
	////////////////////////////////////////////////////////////////////////////
	// The timestamps for the top level files were found ok,
	// however we want to *also* make sure that a full rebuild will be done
	// if any of the dependencies (if we know them) are changed.
	mut cm := vcache.new_cache_manager(b.crun_cache_keys)
	// always rebuild, when the compilation options changed between 2 sequential cruns:
	sbuild_options := cm.load('.build_options', '.crun') or { return true }
	if sbuild_options != b.pref.build_options.join('\n') {
		return true
	}
	sdependencies := cm.load('.dependencies', '.crun') or {
		// empty/wiped out cache, we do not know what the dependencies are, so just
		// rebuild, which will fill in the dependencies cache for the next crun
		return true
	}
	dependencies := sdependencies.split('\n')
	// we have already compiled these source files, and have their dependencies
	dependencies_stamp := most_recent_timestamp(dependencies)
	if dependencies_stamp < exe_stamp {
		return false
	}
	return true
}

fn most_recent_timestamp(files []string) i64 {
	mut res := i64(0)
	for f in files {
		f_stamp := os.file_last_mod_unix(f)
		if res <= f_stamp {
			res = f_stamp
		}
	}
	return res
}

pub fn (mut b Builder) rebuild(backend_cb FnBackend) {
	mut sw := time.new_stopwatch()
	backend_cb(mut b)
	if b.pref.is_crun {
		// save the dependencies after the first compilation, they will be used for subsequent ones:
		mut cm := vcache.new_cache_manager(b.crun_cache_keys)
		dependency_files := b.parsed_files.map(it.path)
		cm.save('.dependencies', '.crun', dependency_files.join('\n')) or {}
		cm.save('.build_options', '.crun', b.pref.build_options.join('\n')) or {}
	}
	mut timers := util.get_timers()
	timers.show_remaining()
	if b.pref.is_stats {
		compilation_time_micros := 1 + sw.elapsed().microseconds()
		scompilation_time_ms := util.bold('${f64(compilation_time_micros) / 1000.0:6.3f}')
		mut all_v_source_lines, mut all_v_source_bytes := 0, 0
		for pf in b.parsed_files {
			all_v_source_lines += pf.nr_lines
			all_v_source_bytes += pf.nr_bytes
		}
		mut sall_v_source_lines := all_v_source_lines.str()
		mut sall_v_source_bytes := all_v_source_bytes.str()
		mut sall_v_types := b.table.type_symbols.len.str()
		mut sall_v_modules := b.table.modules.len.str()
		mut sall_v_files := b.parsed_files.len.str()
		sall_v_source_lines = util.bold('${sall_v_source_lines:10s}')
		sall_v_source_bytes = util.bold('${sall_v_source_bytes:10s}')
		sall_v_types = util.bold('${sall_v_types:5s}')
		sall_v_modules = util.bold('${sall_v_modules:5s}')
		sall_v_files = util.bold('${sall_v_files:5s}')
		println('        V  source  code size: ${sall_v_source_lines} lines, ${sall_v_source_bytes} bytes, ${sall_v_types} types, ${sall_v_modules} modules, ${sall_v_files} files')
		//
		mut slines := b.stats_lines.str()
		mut sbytes := b.stats_bytes.str()
		slines = util.bold('${slines:10s}')
		sbytes = util.bold('${sbytes:10s}')
		println('generated  target  code size: ${slines} lines, ${sbytes} bytes')
		//
		vlines_per_second := int(1_000_000.0 * f64(all_v_source_lines) / f64(compilation_time_micros))
		svlines_per_second := util.bold(vlines_per_second.str())
		println('compilation took: ${scompilation_time_ms} ms, compilation speed: ${svlines_per_second} vlines/s')
	}
}

pub fn (mut b Builder) get_vtmp_filename(base_file_name string, postfix string) string {
	vtmp := os.vtmp_dir()
	mut uniq := ''
	if !b.pref.reuse_tmpc {
		uniq = '.${rand.u64()}'
	}
	fname := os.file_name(os.real_path(base_file_name)) + '${uniq}${postfix}'
	return os.real_path(os.join_path(vtmp, fname))
}
