package org.jenkinsci.plugins.activemq;

import hudson.Extension;
import hudson.model.AbstractProject;
import hudson.model.BuildableItem;
import hudson.model.Item;
import hudson.triggers.Trigger;
import hudson.triggers.TriggerDescriptor;
import hudson.util.FormValidation;
import jenkins.model.Jenkins;
import org.kohsuke.stapler.DataBoundConstructor;
import org.kohsuke.stapler.QueryParameter;
import org.slf4j.Logger;

import javax.script.Invocable;
import javax.script.ScriptEngine;
import javax.script.ScriptException;
import java.util.Map;
import java.util.TreeMap;

import static java.lang.Boolean.TRUE;
import static java.util.Collections.singletonMap;
import static org.apache.commons.lang.StringUtils.trimToNull;
import static org.jenkinsci.plugins.activemq.ActiveMqClient.BuildRequest;
import static org.slf4j.LoggerFactory.getLogger;

public class ActiveMqBuildTrigger extends Trigger<AbstractProject> {

    private static final Logger log = getLogger(ActiveMqBuildTrigger.class);

    private String expression;

    private transient ActiveMqPlugin plugin;

    private transient ScriptEngine engine;

    @DataBoundConstructor
    public ActiveMqBuildTrigger(String expression) {
        log.info("ActiveMqBuildTrigger.ActiveMqBuildTrigger");
        log.info("expression = " + expression);
        this.expression = expression;
    }

    @Override
    public void start(AbstractProject project, boolean newInstance) {
        super.start(project, newInstance);

        plugin = Jenkins.getInstance().getPlugin(ActiveMqPlugin.class);

        log.info("ActiveMqBuildTrigger.start");
        compileExpression();
    }

    public String getExpression() {
        log.info("ActiveMqBuildTrigger.getExpression");
        return expression;
    }

    public void setExpression(String expression) {
        this.expression = expression;
    }

    private void compileExpression() {
        log.info("ActiveMqBuildTrigger.compileExpression: expression={}", expression);

        if (expression == null) {
            return;
        }

        try {
            engine = plugin.createEngine();

            engine.eval(expression);

            if (checkEngine(engine)) {
                log.warn("Invalid expression: {}", expression);
            }
        } catch (Exception e) {
            log.warn("Unable to compile expression", e);
        }
    }

    public boolean matches(BuildRequest req) {
        if (engine == null) {
            return false;
        }

        Map<String, String> parameters = new TreeMap<String, String>(req.parameters);
        Map<String, Map<String, String>> context = singletonMap("parameters", parameters);
        try {
            Object o = ((Invocable) engine).invokeFunction("match", parameters);

            log.info("o = " + o);

            Boolean b = null;
            if (o instanceof Boolean) {
                b = (Boolean) o;
            }

            return b != null && b;
        } catch (Exception e) {
            log.warn("Could not evaluate expression:");
            log.warn(expression);
            log.warn("Context:");
            for (Map.Entry<String, Map<String, String>> entry : context.entrySet()) {
                log.warn("{} = {}", entry.getKey(), entry.getValue());
            }
            log.warn("Exception", e);
            return false;
        }
    }

    @Extension
    public static class DescriptorImpl extends TriggerDescriptor {

        @Override
        public boolean isApplicable(Item item) {
            return item instanceof BuildableItem;
        }

        @Override
        public String getDisplayName() {
            return "ActiveMQ Trigger";
        }

        public FormValidation doCheckExpression(@QueryParameter String expression) {
            log.info("ActiveMqBuildTrigger.doCheckExpression");
            expression = trimToNull(expression);
            if (expression == null) {
                return FormValidation.ok();
            }
            try {
                ActiveMqPlugin plugin = Jenkins.getInstance().getPlugin(ActiveMqPlugin.class);

                ScriptEngine engine = plugin.createEngine();

                engine.eval(expression);

                if (checkEngine(engine)) {
                    return FormValidation.ok();
                }

                return FormValidation.warning("The expression must define a function named 'match'");
            } catch (ScriptException e) {
                return FormValidation.error("Could not evaluate expression: " + e.getMessage());
            } catch (Exception e) {
                return FormValidation.error(e, "Could not evaluate expression");
            }
        }
    }

    private static boolean checkEngine(ScriptEngine engine) throws ScriptException {
        Object o = engine.eval("typeof match === 'function'");

        return TRUE.equals(o);
    }
}