module vbugreport

import net.urllib
import os

const github_bug_issue_form_base_uri = 'https://github.com/vlang/v/issues/new?template=bug-report.yml'
const github_issue_form_url_soft_limit = 7500

pub struct BugReport {
	description  string
	reproduction string
	expected     string
	current      string
	solution     string
	context      string
	version      string
	environment  string
}

struct IssueFormField {
	name  string
	label string
	value string
}

pub enum BugReportDeliveryMode {
	github_form
	local_report
}

pub struct BugReportDelivery {
pub:
	mode              BugReportDeliveryMode
	uri               string
	local_report_path string
	local_report_body string
}

fn field_value_or_default(value string, default_value string) string {
	trimmed := value.trim_space()
	if trimmed.len == 0 {
		return default_value
	}
	return trimmed
}

fn fenced_block(language string, value string) string {
	content := field_value_or_default(value, 'N/A')
	return '```' + language + '\n' + content + '\n```'
}

fn quoted_command(file_path string, generated_file string, user_args string) string {
	mut compile_cmd := './vdbg'
	if user_args.len > 0 {
		compile_cmd += ' ${user_args}'
	}
	compile_cmd += ' ${os.quoted_path(file_path)}'
	return './v -g -o vdbg cmd/v && ${compile_cmd} && ${os.quoted_path(os.real_path(generated_file))}'
}

// new_bug_report builds the structured fields used by the GitHub bug report form.
pub fn new_bug_report(file_path string, generated_file string, user_args string, expected_result string, version string, vdoctor_output string, file_content string, build_output string) BugReport {
	command := quoted_command(file_path, generated_file, user_args)
	source_name := os.file_name(file_path)
	return BugReport{
		description:  'Running `${command}` on `${source_name}` produced a compiler error.'
		reproduction: '${fenced_block('sh', command)}\n\n${fenced_block('v', file_content)}'
		expected:     field_value_or_default(expected_result, 'N/A')
		current:      fenced_block('', build_output)
		solution:     '_No response_'
		context:      'Generated by `v bug` from `${file_path}`.'
		version:      field_value_or_default(version, 'N/A')
		environment:  fenced_block('', vdoctor_output)
	}
}

// issue_form_fields must stay aligned with `.github/ISSUE_TEMPLATE/bug-report.yml`.
fn issue_form_fields(report BugReport) []IssueFormField {
	return [
		IssueFormField{
			name:  'description'
			label: 'Describe the bug'
			value: report.description
		},
		IssueFormField{
			name:  'reproduction'
			label: 'Reproduction Steps'
			value: report.reproduction
		},
		IssueFormField{
			name:  'expected'
			label: 'Expected Behavior'
			value: report.expected
		},
		IssueFormField{
			name:  'current'
			label: 'Current Behavior'
			value: report.current
		},
		IssueFormField{
			name:  'solution'
			label: 'Possible Solution'
			value: report.solution
		},
		IssueFormField{
			name:  'context'
			label: 'Additional Information/Context'
			value: report.context
		},
		IssueFormField{
			name:  'version'
			label: 'V version'
			value: report.version
		},
		IssueFormField{
			name:  'environment'
			label: 'Environment details (OS name and version, etc.)'
			value: report.environment
		},
	]
}

fn github_issue_form_uri(report BugReport) string {
	mut query_params := []string{}
	for field in issue_form_fields(report) {
		query_params << '${field.name}=${urllib.query_escape(field.value)}'
	}
	return '${github_bug_issue_form_base_uri}&${query_params.join('&')}'
}

fn bug_report_markdown(report BugReport) string {
	mut lines := [
		'# V Bug Report',
		'',
		'Generated by `v bug`.',
		'',
	]
	for field in issue_form_fields(report) {
		lines << '### ${field.label}'
		lines << ''
		lines << field.value
		lines << ''
	}
	return lines.join('\n')
}

fn bug_report_file_path(file_path string) string {
	base_name := os.file_name(file_path)
	stem := if base_name.contains('.') { base_name.all_before_last('.') } else { base_name }
	file_name := if stem.len == 0 { 'v-bug-report.md' } else { '${stem}.bug-report.md' }
	file_dir := os.dir(file_path)
	return if file_dir.len == 0 || file_dir == '.' {
		file_name
	} else {
		os.join_path(file_dir, file_name)
	}
}

// prepare_bug_report_delivery chooses between a prefilled issue-form URL and a local markdown fallback.
pub fn prepare_bug_report_delivery(report BugReport, file_path string) BugReportDelivery {
	uri := github_issue_form_uri(report)
	if uri.len <= github_issue_form_url_soft_limit {
		return BugReportDelivery{
			mode: .github_form
			uri:  uri
		}
	}
	return BugReportDelivery{
		mode:              .local_report
		uri:               github_bug_issue_form_base_uri
		local_report_path: bug_report_file_path(file_path)
		local_report_body: bug_report_markdown(report)
	}
}